crypto

crypto(3erl)                Erlang Module Definition                crypto(3erl)



NAME
       crypto - Crypto Functions

DESCRIPTION
       This module provides a set of cryptographic functions.

         Hash functions:


           SHA1, SHA2:
              Secure Hash Standard [FIPS PUB 180-4]

           SHA3:
              SHA-3 Standard: Permutation-Based Hash and Extendable-Output
             Functions [FIPS PUB 202]

           MD5:
             The MD5 Message Digest Algorithm [RFC 1321]

           MD4:
             The MD4 Message Digest Algorithm [RFC 1320]

         MACs - Message Authentication Codes:


           Hmac functions:
              Keyed-Hashing for Message Authentication [RFC 2104]

           Cmac functions:
              The AES-CMAC Algorithm [RFC 4493]

           POLY1305:
              ChaCha20 and Poly1305 for IETF Protocols [RFC 7539]

         Symmetric Ciphers:


           DES, 3DES and AES:
             Block Cipher Techniques [NIST]

           Blowfish:
              Fast Software Encryption, Cambridge Security Workshop Proceedings
             (December 1993), Springer-Verlag, 1994, pp. 191-204.

           Chacha20:
              ChaCha20 and Poly1305 for IETF Protocols [RFC 7539]

           Chacha20_poly1305:
              ChaCha20 and Poly1305 for IETF Protocols [RFC 7539]

         Modes:


           ECB, CBC, CFB, OFB and CTR:
              Recommendation for Block Cipher Modes of Operation: Methods and
             Techniques [NIST SP 800-38A]

           GCM:
              Recommendation for Block Cipher Modes of Operation: Galois/Counter
             Mode (GCM) and GMAC [NIST SP 800-38D]

           CCM:
              Recommendation for Block Cipher Modes of Operation: The CCM Mode
             for Authentication and Confidentiality [NIST SP 800-38C]

         Asymetric Ciphers - Public Key Techniques:


           RSA:
              PKCS #1: RSA Cryptography Specifications [RFC 3447]

           DSS:
              Digital Signature Standard (DSS) [FIPS 186-4]

           ECDSA:
              Elliptic Curve Digital Signature Algorithm [ECDSA]

           SRP:
              The SRP Authentication and Key Exchange System [RFC 2945]

   Note:
       The actual supported algorithms and features depends on their
       availability in the actual libcrypto used. See the crypto (App) about
       dependencies.

       Enabling FIPS mode will also disable algorithms and features.


       The CRYPTO User's Guide has more information on FIPS, Engines and
       Algorithm Details like key lengths.

DATA TYPES
   Ciphers
       stream_cipher() = rc4 | aes_ctr | chacha20

              Stream ciphers for stream_encrypt/2 and stream_decrypt/2 .


       block_cipher_with_iv() =
           cbc_cipher() |
           cfb_cipher() |
           aes_cbc128 |
           aes_cbc256 |
           aes_ige256 |
           blowfish_ofb64 |
           des3_cbf |
           des_ede3 |
           rc2_cbc

       cbc_cipher() = des_cbc | des3_cbc | aes_cbc | blowfish_cbc

       cfb_cipher() =
           aes_cfb128 | aes_cfb8 | blowfish_cfb64 | des3_cfb | des_cfb

              Block ciphers with initialization vector for block_encrypt/4 and
              block_decrypt/4 .


       block_cipher_without_iv() = ecb_cipher()

       ecb_cipher() = des_ecb | blowfish_ecb | aes_ecb

              Block ciphers without initialization vector for block_encrypt/3
              and block_decrypt/3 .


       aead_cipher() = aes_gcm | aes_ccm | chacha20_poly1305

              Ciphers with simultaneous MAC-calculation or MAC-checking.
              block_encrypt/4 and block_decrypt/4 .


   Digests
       sha1() = sha

       sha2() = sha224 | sha256 | sha384 | sha512

       sha3() = sha3_224 | sha3_256 | sha3_384 | sha3_512


       compatibility_only_hash() = md5 | md4

              The compatibility_only_hash() algorithms are recommended only for
              compatibility with existing applications.


       rsa_digest_type() = sha1() | sha2() | md5 | ripemd160


       dss_digest_type() = sha1() | sha2()


       ecdsa_digest_type() = sha1() | sha2()


   Elliptic Curves
       ec_named_curve() =
           brainpoolP160r1 |
           brainpoolP160t1 |
           brainpoolP192r1 |
           brainpoolP192t1 |
           brainpoolP224r1 |
           brainpoolP224t1 |
           brainpoolP256r1 |
           brainpoolP256t1 |
           brainpoolP320r1 |
           brainpoolP320t1 |
           brainpoolP384r1 |
           brainpoolP384t1 |
           brainpoolP512r1 |
           brainpoolP512t1 |
           c2pnb163v1 |
           c2pnb163v2 |
           c2pnb163v3 |
           c2pnb176v1 |
           c2pnb208w1 |
           c2pnb272w1 |
           c2pnb304w1 |
           c2pnb368w1 |
           c2tnb191v1 |
           c2tnb191v2 |
           c2tnb191v3 |
           c2tnb239v1 |
           c2tnb239v2 |
           c2tnb239v3 |
           c2tnb359v1 |
           c2tnb431r1 |
           ipsec3 |
           ipsec4 |
           prime192v1 |
           prime192v2 |
           prime192v3 |
           prime239v1 |
           prime239v2 |
           prime239v3 |
           prime256v1 |
           secp112r1 |
           secp112r2 |
           secp128r1 |
           secp128r2 |
           secp160k1 |
           secp160r1 |
           secp160r2 |
           secp192k1 |
           secp192r1 |
           secp224k1 |
           secp224r1 |
           secp256k1 |
           secp256r1 |
           secp384r1 |
           secp521r1 |
           sect113r1 |
           sect113r2 |
           sect131r1 |
           sect131r2 |
           sect163k1 |
           sect163r1 |
           sect163r2 |
           sect193r1 |
           sect193r2 |
           sect233k1 |
           sect233r1 |
           sect239k1 |
           sect283k1 |
           sect283r1 |
           sect409k1 |
           sect409r1 |
           sect571k1 |
           sect571r1 |
           wtls1 |
           wtls10 |
           wtls11 |
           wtls12 |
           wtls3 |
           wtls4 |
           wtls5 |
           wtls6 |
           wtls7 |
           wtls8 |
           wtls9

       edwards_curve_dh() = x25519 | x448

       edwards_curve_ed() = ed25519 | ed448

              Note that some curves are disabled if FIPS is enabled.


       ec_explicit_curve() =
           {Field :: ec_field(),
            Curve :: ec_curve(),
            BasePoint :: binary(),
            Order :: binary(),
            CoFactor :: none | binary()}

       ec_field() = ec_prime_field() | ec_characteristic_two_field()

       ec_curve() =
           {A :: binary(), B :: binary(), Seed :: none | binary()}

              Parametric curve definition.


       ec_prime_field() = {prime_field, Prime :: integer()}

       ec_characteristic_two_field() =
           {characteristic_two_field,
            M :: integer(),
            Basis :: ec_basis()}

       ec_basis() =
           {tpbasis, K :: integer() >= 0} |
           {ppbasis,
            K1 :: integer() >= 0,
            K2 :: integer() >= 0,
            K3 :: integer() >= 0} |
           onbasis

              Curve definition details.


   Keys
       key() = iodata()

       des3_key() = [key()]

              For keylengths, iv-sizes and blocksizes see the User's Guide.

              A key for des3 is a list of three iolists


       key_integer() = integer() | binary()

              Always binary() when used as return value


   Public/Private Keys
       rsa_public() = [key_integer()]

       rsa_private() = [key_integer()]

       rsa_params() =
           {ModulusSizeInBits :: integer(),
            PublicExponent :: key_integer()}

              rsa_public() = [E, N]

              rsa_private() = [E, N, D] | [E, N, D, P1, P2, E1, E2, C]

              Where E is the public exponent, N is public modulus and D is the
              private exponent. The longer key format contains redundant
              information that will make the calculation faster. P1,P2 are first
              and second prime factors. E1,E2 are first and second exponents. C
              is the CRT coefficient. Terminology is taken from  RFC 3447.


       dss_public() = [key_integer()]

       dss_private() = [key_integer()]

              dss_public() = [P, Q, G, Y]

              Where P, Q and G are the dss parameters and Y is the public key.

              dss_private() = [P, Q, G, X]

              Where P, Q and G are the dss parameters and X is the private key.


       ecdsa_public() = key_integer()

       ecdsa_private() = key_integer()

       ecdsa_params() = ec_named_curve() | ec_explicit_curve()


       eddsa_public() = key_integer()

       eddsa_private() = key_integer()

       eddsa_params() = edwards_curve_ed()


       srp_public() = key_integer()

       srp_private() = key_integer()

              srp_public() = key_integer()

              Where is A or B from SRP design

              srp_private() = key_integer()

              Where is a or b from SRP design


       srp_gen_params() =
           {user, srp_user_gen_params()} | {host, srp_host_gen_params()}

       srp_comp_params() =
           {user, srp_user_comp_params()} |
           {host, srp_host_comp_params()}

              srp_user_gen_params() = [DerivedKey::binary(), Prime::binary(), Generator::binary(), Version::atom()]

              srp_host_gen_params() = [Verifier::binary(), Prime::binary(), Version::atom() ]

              srp_user_comp_params() = [DerivedKey::binary(), Prime::binary(), Generator::binary(), Version::atom() | ScramblerArg::list()]

              srp_host_comp_params() = [Verifier::binary(), Prime::binary(), Version::atom() | ScramblerArg::list()]

              Where Verifier is v, Generator is g and Prime is N, DerivedKey is
              X, and Scrambler is u (optional will be generated if not provided)
              from SRP design Version = '3' | '6' | '6a'


   Public Key Ciphers
       pk_encrypt_decrypt_algs() = rsa

              Algorithms for public key encrypt/decrypt. Only RSA is supported.


       pk_encrypt_decrypt_opts() = [rsa_opt()] | rsa_compat_opts()

       rsa_opt() =
           {rsa_padding, rsa_padding()} |
           {signature_md, atom()} |
           {rsa_mgf1_md, sha} |
           {rsa_oaep_label, binary()} |
           {rsa_oaep_md, sha}

       rsa_padding() =
           rsa_pkcs1_padding |
           rsa_pkcs1_oaep_padding |
           rsa_sslv23_padding |
           rsa_x931_padding |
           rsa_no_padding

              Options for public key encrypt/decrypt. Only RSA is supported.

          Warning:

              The RSA options are experimental.

              The exact set of options and there syntax may be changed without
              prior notice.



       rsa_compat_opts() = [{rsa_pad, rsa_padding()}] | rsa_padding()

              Those option forms are kept only for compatibility and should not
              be used in new code.


   Public Key Sign and Verify
       pk_sign_verify_algs() = rsa | dss | ecdsa | eddsa

              Algorithms for sign and verify.


       pk_sign_verify_opts() = [rsa_sign_verify_opt()]

       rsa_sign_verify_opt() =
           {rsa_padding, rsa_sign_verify_padding()} |
           {rsa_pss_saltlen, integer()}

       rsa_sign_verify_padding() =
           rsa_pkcs1_padding |
           rsa_pkcs1_pss_padding |
           rsa_x931_padding |
           rsa_no_padding

              Options for sign and verify.

          Warning:

              The RSA options are experimental.

              The exact set of options and there syntax may be changed without
              prior notice.



   Diffie-Hellman Keys and parameters
       dh_public() = key_integer()

       dh_private() = key_integer()


       dh_params() = [key_integer()]

              dh_params() = [P, G] | [P, G, PrivateKeyBitLength]


       ecdh_public() = key_integer()

       ecdh_private() = key_integer()

       ecdh_params() =
           ec_named_curve() | edwards_curve_dh() | ec_explicit_curve()


   Types for Engines
       engine_key_ref() =
           #{engine := engine_ref(),
             key_id := key_id(),
             password => password(),
             term() => term()}

       engine_ref() = term()

              The result of a call to engine_load/3.


       key_id() = string() | binary()

              Identifies the key to be used. The format depends on the loaded
              engine. It is passed to the ENGINE_load_(private|public)_key
              functions in libcrypto.


       password() = string() | binary()

              The password of the key stored in an engine.


       engine_method_type() =
           engine_method_rsa |
           engine_method_dsa |
           engine_method_dh |
           engine_method_rand |
           engine_method_ecdh |
           engine_method_ecdsa |
           engine_method_ciphers |
           engine_method_digests |
           engine_method_store |
           engine_method_pkey_meths |
           engine_method_pkey_asn1_meths |
           engine_method_ec

       engine_cmnd() = {unicode:chardata(), unicode:chardata()}

              Pre and Post commands for engine_load/3 and /4.


   Internal data types
       stream_state()

       hmac_state()

       hash_state()

              Contexts with an internal state that should not be manipulated but
              passed between function calls.


EXPORTS
       block_encrypt(Type :: block_cipher_without_iv(),
                     Key :: key(),
                     PlainText :: iodata()) ->
                        binary()

              Encrypt PlainText according to Type block cipher.

              May raise exception error:notsup in case the chosen Type is not
              supported by the underlying libcrypto implementation.

              For keylengths and blocksizes see the User's Guide.


       block_decrypt(Type :: block_cipher_without_iv(),
                     Key :: key(),
                     Data :: iodata()) ->
                        binary()

              Decrypt CipherText according to Type block cipher.

              May raise exception error:notsup in case the chosen Type is not
              supported by the underlying libcrypto implementation.

              For keylengths and blocksizes see the User's Guide.


       block_encrypt(Type, Key, Ivec, PlainText) -> CipherText
       block_encrypt(AeadType, Key, Ivec, {AAD, PlainText}) -> {CipherText,
       CipherTag}
       block_encrypt(aes_gcm | aes_ccm, Key, Ivec, {AAD, PlainText, TagLength})
       -> {CipherText, CipherTag}

              Types:

                 Type = block_cipher_with_iv()
                 AeadType = aead_cipher()
                 Key = key() | des3_key()
                 PlainText = iodata()
                 AAD = IVec = CipherText = CipherTag = binary()
                 TagLength = 1..16

              Encrypt PlainText according to Type block cipher. IVec is an
              arbitrary initializing vector.

              In AEAD (Authenticated Encryption with Associated Data) mode,
              encrypt PlainTextaccording to Type block cipher and calculate
              CipherTag that also authenticates the AAD (Associated
              Authenticated Data).

              May raise exception error:notsup in case the chosen Type is not
              supported by the underlying libcrypto implementation.

              For keylengths, iv-sizes and blocksizes see the User's Guide.


       block_decrypt(Type, Key, Ivec, CipherText) -> PlainText
       block_decrypt(AeadType, Key, Ivec, {AAD, CipherText, CipherTag}) ->
       PlainText | error

              Types:

                 Type = block_cipher_with_iv()
                 AeadType = aead_cipher()
                 Key = key() | des3_key()
                 PlainText = iodata()
                 AAD = IVec = CipherText = CipherTag = binary()

              Decrypt CipherText according to Type block cipher. IVec is an
              arbitrary initializing vector.

              In AEAD (Authenticated Encryption with Associated Data) mode,
              decrypt CipherTextaccording to Type block cipher and check the
              authenticity the PlainText and AAD (Associated Authenticated Data)
              using the CipherTag. May return error if the decryption or
              validation fail's

              May raise exception error:notsup in case the chosen Type is not
              supported by the underlying libcrypto implementation.

              For keylengths, iv-sizes and blocksizes see the User's Guide.


       bytes_to_integer(Bin :: binary()) -> integer()

              Convert binary representation, of an integer, to an Erlang
              integer.


       compute_key(Type, OthersPublicKey, MyPrivateKey, Params) ->
                      SharedSecret

              Types:

                 Type = dh | ecdh | srp
                 SharedSecret = binary()
                 OthersPublicKey = dh_public() | ecdh_public() | srp_public()
                 MyPrivateKey =
                     dh_private() | ecdh_private() | {srp_public(),
                 srp_private()}
                 Params = dh_params() | ecdh_params() | srp_comp_params()

              Computes the shared secret from the private key and the other
              party's public key. See also public_key:compute_key/2


       exor(Bin1 :: iodata(), Bin2 :: iodata()) -> binary()

              Performs bit-wise XOR (exclusive or) on the data supplied.


       generate_key(Type, Params) -> {PublicKey, PrivKeyOut}

       generate_key(Type, Params, PrivKeyIn) -> {PublicKey, PrivKeyOut}

              Types:

                 Type = dh | ecdh | rsa | srp
                 PublicKey =
                     dh_public() | ecdh_public() | rsa_public() | srp_public()
                 PrivKeyIn =
                     undefined |
                     dh_private() |
                     ecdh_private() |
                     rsa_private() |
                     {srp_public(), srp_private()}
                 PrivKeyOut =
                     dh_private() |
                     ecdh_private() |
                     rsa_private() |
                     {srp_public(), srp_private()}
                 Params =
                     dh_params() | ecdh_params() | rsa_params() |
                 srp_comp_params()

              Generates a public key of type Type. See also
              public_key:generate_key/1. May raise exception:

                * error:badarg: an argument is of wrong type or has an illegal
                  value,

                * error:low_entropy: the random generator failed due to lack of
                  secure "randomness",

                * error:computation_failed: the computation fails of another
                  reason than low_entropy.

          Note:
              RSA key generation is only available if the runtime was built with
              dirty scheduler support. Otherwise, attempting to generate an RSA
              key will raise exception error:notsup.



       hash(Type, Data) -> Digest

              Types:

                 Type =
                     sha1() |
                     sha2() |
                     sha3() |
                     ripemd160 |
                     compatibility_only_hash()
                 Data = iodata()
                 Digest = binary()

              Computes a message digest of type Type from Data.

              May raise exception error:notsup in case the chosen Type is not
              supported by the underlying libcrypto implementation.


       hash_init(Type) -> State

              Types:

                 Type =
                     sha1() |
                     sha2() |
                     sha3() |
                     ripemd160 |
                     compatibility_only_hash()
                 State = hash_state()

              Initializes the context for streaming hash operations. Type
              determines which digest to use. The returned context should be
              used as argument to hash_update.

              May raise exception error:notsup in case the chosen Type is not
              supported by the underlying libcrypto implementation.


       hash_update(State, Data) -> NewState

              Types:

                 State = NewState = hash_state()
                 Data = iodata()

              Updates the digest represented by Context using the given Data.
              Context must have been generated using hash_init or a previous
              call to this function. Data can be any length. NewContext must be
              passed into the next call to hash_update or hash_final.


       hash_final(State) -> Digest

              Types:

                 State = hash_state()
                 Digest = binary()

              Finalizes the hash operation referenced by Context returned from a
              previous call to hash_update. The size of Digest is determined by
              the type of hash function used to generate it.


       hmac(Type, Key, Data) -> Mac

       hmac(Type, Key, Data, MacLength) -> Mac

              Types:

                 Type = sha1() | sha2() | sha3() | compatibility_only_hash()
                 Key = Data = iodata()
                 MacLength = integer()
                 Mac = binary()

              Computes a HMAC of type Type from Data using Key as the
              authentication key.

              MacLength will limit the size of the resultant Mac.


       hmac_init(Type, Key) -> State

              Types:

                 Type = sha1() | sha2() | sha3() | compatibility_only_hash()
                 Key = iodata()
                 State = hmac_state()

              Initializes the context for streaming HMAC operations. Type
              determines which hash function to use in the HMAC operation. Key
              is the authentication key. The key can be any length.


       hmac_update(State, Data) -> NewState

              Types:

                 Data = iodata()
                 State = NewState = hmac_state()

              Updates the HMAC represented by Context using the given Data.
              Context must have been generated using an HMAC init function (such
              as hmac_init). Data can be any length. NewContext must be passed
              into the next call to hmac_update or to one of the functions
              hmac_final and hmac_final_n

          Warning:
              Do not use a Context as argument in more than one call to
              hmac_update or hmac_final. The semantics of reusing old contexts
              in any way is undefined and could even crash the VM in earlier
              releases. The reason for this limitation is a lack of support in
              the underlying libcrypto API.



       hmac_final(State) -> Mac

              Types:

                 State = hmac_state()
                 Mac = binary()

              Finalizes the HMAC operation referenced by Context. The size of
              the resultant MAC is determined by the type of hash function used
              to generate it.


       hmac_final_n(State, HashLen) -> Mac

              Types:

                 State = hmac_state()
                 HashLen = integer()
                 Mac = binary()

              Finalizes the HMAC operation referenced by Context. HashLen must
              be greater than zero. Mac will be a binary with at most HashLen
              bytes. Note that if HashLen is greater than the actual number of
              bytes returned from the underlying hash, the returned hash will
              have fewer than HashLen bytes.


       cmac(Type, Key, Data) -> Mac

       cmac(Type, Key, Data, MacLength) -> Mac

              Types:

                 Type =
                     cbc_cipher() |
                     cfb_cipher() |
                     blowfish_cbc |
                     des_ede3 |
                     rc2_cbc
                 Key = Data = iodata()
                 MacLength = integer()
                 Mac = binary()

              Computes a CMAC of type Type from Data using Key as the
              authentication key.

              MacLength will limit the size of the resultant Mac.


       info_fips() -> not_supported | not_enabled | enabled

              Provides information about the FIPS operating status of crypto and
              the underlying libcrypto library. If crypto was built with FIPS
              support this can be either enabled (when running in FIPS mode) or
              not_enabled. For other builds this value is always not_supported.

              See enable_fips_mode/1 about how to enable FIPS mode.

          Warning:
              In FIPS mode all non-FIPS compliant algorithms are disabled and
              raise exception error:notsup. Check supports that in FIPS mode
              returns the restricted list of available algorithms.



       enable_fips_mode(Enable) -> Result

              Types:

                 Enable = Result = boolean()

              Enables (Enable = true) or disables (Enable = false) FIPS mode.
              Returns true if the operation was successful or false otherwise.

              Note that to enable FIPS mode succesfully, OTP must be built with
              the configure option --enable-fips, and the underlying libcrypto
              must also support FIPS.

              See also info_fips/0.


       info_lib() -> [{Name, VerNum, VerStr}]

              Types:

                 Name = binary()
                 VerNum = integer()
                 VerStr = binary()

              Provides the name and version of the libraries used by crypto.

              Name is the name of the library. VerNum is the numeric version
              according to the library's own versioning scheme. VerStr contains
              a text variant of the version.

              > info_lib().
              [{<<"OpenSSL">>,269484095,<<"OpenSSL 1.1.0c  10 Nov 2016"">>}]


          Note:
              From OTP R16 the numeric version represents the version of the
              OpenSSL header files (openssl/opensslv.h) used when crypto was
              compiled. The text variant represents the libcrypto library used
              at runtime. In earlier OTP versions both numeric and text was
              taken from the library.



       mod_pow(N, P, M) -> Result

              Types:

                 N = P = M = binary() | integer()
                 Result = binary() | error

              Computes the function N^P mod M.


       next_iv(Type :: cbc_cipher(), Data) -> NextIVec

       next_iv(Type :: des_cfb, Data, IVec) -> NextIVec

              Types:

                 Data = iodata()
                 IVec = NextIVec = binary()

              Returns the initialization vector to be used in the next iteration
              of encrypt/decrypt of type Type. Data is the encrypted data from
              the previous iteration step. The IVec argument is only needed for
              des_cfb as the vector used in the previous iteration step.


       poly1305(Key :: iodata(), Data :: iodata()) -> Mac

              Types:

                 Mac = binary()

              Computes a POLY1305 message authentication code (Mac) from Data
              using Key as the authentication key.


       private_decrypt(Algorithm, CipherText, PrivateKey, Options) ->
                          PlainText

              Types:

                 Algorithm = pk_encrypt_decrypt_algs()
                 CipherText = binary()
                 PrivateKey = rsa_private() | engine_key_ref()
                 Options = pk_encrypt_decrypt_opts()
                 PlainText = binary()

              Decrypts the CipherText, encrypted with public_encrypt/4 (or
              equivalent function) using the PrivateKey, and returns the
              plaintext (message digest). This is a low level signature
              verification operation used for instance by older versions of the
              SSL protocol. See also public_key:decrypt_private/[2,3]


       private_encrypt(Algorithm, PlainText, PrivateKey, Options) ->
                          CipherText

              Types:

                 Algorithm = pk_encrypt_decrypt_algs()
                 PlainText = binary()
                 PrivateKey = rsa_private() | engine_key_ref()
                 Options = pk_encrypt_decrypt_opts()
                 CipherText = binary()

              Encrypts the PlainText using the PrivateKey and returns the
              ciphertext. This is a low level signature operation used for
              instance by older versions of the SSL protocol. See also
              public_key:encrypt_private/[2,3]


       public_decrypt(Algorithm, CipherText, PublicKey, Options) ->
                         PlainText

              Types:

                 Algorithm = pk_encrypt_decrypt_algs()
                 CipherText = binary()
                 PublicKey = rsa_public() | engine_key_ref()
                 Options = pk_encrypt_decrypt_opts()
                 PlainText = binary()

              Decrypts the CipherText, encrypted with private_encrypt/4(or
              equivalent function) using the PrivateKey, and returns the
              plaintext (message digest). This is a low level signature
              verification operation used for instance by older versions of the
              SSL protocol. See also public_key:decrypt_public/[2,3]


       public_encrypt(Algorithm, PlainText, PublicKey, Options) ->
                         CipherText

              Types:

                 Algorithm = pk_encrypt_decrypt_algs()
                 PlainText = binary()
                 PublicKey = rsa_public() | engine_key_ref()
                 Options = pk_encrypt_decrypt_opts()
                 CipherText = binary()

              Encrypts the PlainText (message digest) using the PublicKey and
              returns the CipherText. This is a low level signature operation
              used for instance by older versions of the SSL protocol. See also
              public_key:encrypt_public/[2,3]


       rand_seed(Seed :: binary()) -> ok

              Set the seed for PRNG to the given binary. This calls the
              RAND_seed function from openssl. Only use this if the system you
              are running on does not have enough "randomness" built in.
              Normally this is when strong_rand_bytes/1 raises error:low_entropy


       rand_uniform(Lo, Hi) -> N

              Types:

                 Lo, Hi, N = integer()

              Generate a random number N, Lo =< N < Hi. Uses the crypto library
              pseudo-random number generator. Hi must be larger than Lo.


       start() -> ok | {error, Reason :: term()}

              Equivalent to application:start(crypto).


       stop() -> ok | {error, Reason :: term()}

              Equivalent to application:stop(crypto).


       strong_rand_bytes(N :: integer() >= 0) -> binary()

              Generates N bytes randomly uniform 0..255, and returns the result
              in a binary. Uses a cryptographically secure prng seeded and
              periodically mixed with operating system provided entropy. By
              default this is the RAND_bytes method from OpenSSL.

              May raise exception error:low_entropy in case the random generator
              failed due to lack of secure "randomness".


       rand_seed() -> rand:state()

              Creates state object for random number generation, in order to
              generate cryptographically strong random numbers (based on
              OpenSSL's BN_rand_range), and saves it in the process dictionary
              before returning it as well. See also rand:seed/1 and
              rand_seed_s/0.

              When using the state object from this function the rand functions
              using it may raise exception error:low_entropy in case the random
              generator failed due to lack of secure "randomness".

              Example

              _ = crypto:rand_seed(),
              _IntegerValue = rand:uniform(42), % [1; 42]
              _FloatValue = rand:uniform().     % [0.0; 1.0[


       rand_seed_s() -> rand:state()

              Creates state object for random number generation, in order to
              generate cryptographically strongly random numbers (based on
              OpenSSL's BN_rand_range). See also rand:seed_s/1.

              When using the state object from this function the rand functions
              using it may raise exception error:low_entropy in case the random
              generator failed due to lack of secure "randomness".

          Note:
              The state returned from this function can not be used to get a
              reproducable random sequence as from the other rand functions,
              since reproducability does not match cryptographically safe.

              The only supported usage is to generate one distinct random
              sequence from this start state.



       rand_seed_alg(Alg) -> rand:state()

              Types:

                 Alg = crypto | crypto_cache

              Creates state object for random number generation, in order to
              generate cryptographically strong random numbers. See also
              rand:seed/1 and rand_seed_alg_s/1.

              When using the state object from this function the rand functions
              using it may raise exception error:low_entropy in case the random
              generator failed due to lack of secure "randomness".

              The cache size can be changed from its default value using the
              crypto app's  configuration parameter rand_cache_size.

              Example

              _ = crypto:rand_seed_alg(crypto_cache),
              _IntegerValue = rand:uniform(42), % [1; 42]
              _FloatValue = rand:uniform().     % [0.0; 1.0[


       rand_seed_alg_s(Alg) -> rand:state()

              Types:

                 Alg = crypto | crypto_cache

              Creates state object for random number generation, in order to
              generate cryptographically strongly random numbers. See also
              rand:seed_s/1.

              If Alg is crypto this function behaves exactly like rand_seed_s/0.

              If Alg is crypto_cache this function fetches random data with
              OpenSSL's RAND_bytes and caches it for speed using an internal
              word size of 56 bits that makes calculations fast on 64 bit
              machines.

              When using the state object from this function the rand functions
              using it may raise exception error:low_entropy in case the random
              generator failed due to lack of secure "randomness".

              The cache size can be changed from its default value using the
              crypto app's  configuration parameter rand_cache_size.

          Note:
              The state returned from this function can not be used to get a
              reproducable random sequence as from the other rand functions,
              since reproducability does not match cryptographically safe.

              In fact since random data is cached some numbers may get
              reproduced if you try, but this is unpredictable.

              The only supported usage is to generate one distinct random
              sequence from this start state.



       stream_init(Type, Key) -> State

              Types:

                 Type = rc4
                 Key = iodata()
                 State = stream_state()

              Initializes the state for use in RC4 stream encryption
              stream_encrypt and stream_decrypt

              For keylengths see the User's Guide.


       stream_init(Type, Key, IVec) -> State

              Types:

                 Type = aes_ctr | chacha20
                 Key = iodata()
                 IVec = binary()
                 State = stream_state()

              Initializes the state for use in streaming AES encryption using
              Counter mode (CTR). Key is the AES key and must be either 128,
              192, or 256 bits long. IVec is an arbitrary initializing vector of
              128 bits (16 bytes). This state is for use with stream_encrypt and
              stream_decrypt.

              For keylengths and iv-sizes see the User's Guide.


       stream_encrypt(State, PlainText) -> {NewState, CipherText}

              Types:

                 State = stream_state()
                 PlainText = iodata()
                 NewState = stream_state()
                 CipherText = iodata()

              Encrypts PlainText according to the stream cipher Type specified
              in stream_init/3. Text can be any number of bytes. The initial
              State is created using stream_init. NewState must be passed into
              the next call to stream_encrypt.


       stream_decrypt(State, CipherText) -> {NewState, PlainText}

              Types:

                 State = stream_state()
                 CipherText = iodata()
                 NewState = stream_state()
                 PlainText = iodata()

              Decrypts CipherText according to the stream cipher Type specified
              in stream_init/3. PlainText can be any number of bytes. The
              initial State is created using stream_init. NewState must be
              passed into the next call to stream_decrypt.


       supports() -> [Support]

              Types:

                 Support =
                     {hashs, Hashs} |
                     {ciphers, Ciphers} |
                     {public_keys, PKs} |
                     {macs, Macs} |
                     {curves, Curves} |
                     {rsa_opts, RSAopts}
                 Hashs =
                     [sha1() |
                      sha2() |
                      sha3() |
                      ripemd160 |
                      compatibility_only_hash()]
                 Ciphers =
                     [stream_cipher() |
                      block_cipher_with_iv() |
                      block_cipher_without_iv() |
                      aead_cipher()]
                 PKs = [rsa | dss | ecdsa | dh | ecdh | ec_gf2m]
                 Macs = [hmac | cmac | poly1305]
                 Curves =
                     [ec_named_curve() | edwards_curve_dh() |
                 edwards_curve_ed()]
                 RSAopts = [rsa_sign_verify_opt() | rsa_opt()]

              Can be used to determine which crypto algorithms that are
              supported by the underlying libcrypto library

              Note: the rsa_opts entry is in an experimental state and may
              change or be removed without notice. No guarantee for the accuarcy
              of the rsa option's value list should be assumed.


       ec_curves() -> [EllipticCurve]

              Types:

                 EllipticCurve =
                     ec_named_curve() | edwards_curve_dh() | edwards_curve_ed()

              Can be used to determine which named elliptic curves are
              supported.


       ec_curve(CurveName) -> ExplicitCurve

              Types:

                 CurveName = ec_named_curve()
                 ExplicitCurve = ec_explicit_curve()

              Return the defining parameters of a elliptic curve.


       sign(Algorithm, DigestType, Msg, Key) -> Signature

       sign(Algorithm, DigestType, Msg, Key, Options) -> Signature

              Types:

                 Algorithm = pk_sign_verify_algs()
                 DigestType =
                     rsa_digest_type() |
                     dss_digest_type() |
                     ecdsa_digest_type() |
                     none
                 Msg = binary() | {digest, binary()}
                 Key =
                     rsa_private() |
                     dss_private() |
                     [ecdsa_private() | ecdsa_params()] |
                     [eddsa_private() | eddsa_params()] |
                     engine_key_ref()
                 Options = pk_sign_verify_opts()
                 Signature = binary()

              Creates a digital signature.

              The msg is either the binary "cleartext" data to be signed or it
              is the hashed value of "cleartext" i.e. the digest (plaintext).

              Algorithm dss can only be used together with digest type sha.

              See also public_key:sign/3.


       verify(Algorithm, DigestType, Msg, Signature, Key) -> Result

       verify(Algorithm, DigestType, Msg, Signature, Key, Options) ->
                 Result

              Types:

                 Algorithm = pk_sign_verify_algs()
                 DigestType =
                     rsa_digest_type() | dss_digest_type() | ecdsa_digest_type()
                 Msg = binary() | {digest, binary()}
                 Signature = binary()
                 Key =
                     rsa_public() |
                     dss_public() |
                     [ecdsa_public() | ecdsa_params()] |
                     [eddsa_public() | eddsa_params()] |
                     engine_key_ref()
                 Options = pk_sign_verify_opts()
                 Result = boolean()

              Verifies a digital signature

              The msg is either the binary "cleartext" data to be signed or it
              is the hashed value of "cleartext" i.e. the digest (plaintext).

              Algorithm dss can only be used together with digest type sha.

              See also public_key:verify/4.


       privkey_to_pubkey(Type, EnginePrivateKeyRef) -> PublicKey

              Types:

                 Type = rsa | dss
                 EnginePrivateKeyRef = engine_key_ref()
                 PublicKey = rsa_public() | dss_public()

              Fetches the corresponding public key from a private key stored in
              an Engine. The key must be of the type indicated by the Type
              parameter.


       engine_get_all_methods() -> Result

              Types:

                 Result = [engine_method_type()]

              Returns a list of all possible engine methods.

              May raise exception error:notsup in case there is no engine
              support in the underlying OpenSSL implementation.

              See also the chapter Engine Load in the User's Guide.


       engine_load(EngineId, PreCmds, PostCmds) -> Result

              Types:

                 EngineId = unicode:chardata()
                 PreCmds = PostCmds = [engine_cmnd()]
                 Result =
                     {ok, Engine :: engine_ref()} | {error, Reason :: term()}

              Loads the OpenSSL engine given by EngineId if it is available and
              then returns ok and an engine handle. This function is the same as
              calling engine_load/4 with EngineMethods set to a list of all the
              possible methods. An error tuple is returned if the engine can't
              be loaded.

              The function raises a error:badarg if the parameters are in wrong
              format. It may also raise the exception error:notsup in case there
              is no engine support in the underlying OpenSSL implementation.

              See also the chapter Engine Load in the User's Guide.


       engine_load(EngineId, PreCmds, PostCmds, EngineMethods) -> Result

              Types:

                 EngineId = unicode:chardata()
                 PreCmds = PostCmds = [engine_cmnd()]
                 EngineMethods = [engine_method_type()]
                 Result =
                     {ok, Engine :: engine_ref()} | {error, Reason :: term()}

              Loads the OpenSSL engine given by EngineId if it is available and
              then returns ok and an engine handle. An error tuple is returned
              if the engine can't be loaded.

              The function raises a error:badarg if the parameters are in wrong
              format. It may also raise the exception error:notsup in case there
              is no engine support in the underlying OpenSSL implementation.

              See also the chapter Engine Load in the User's Guide.


       engine_unload(Engine) -> Result

              Types:

                 Engine = engine_ref()
                 Result = ok | {error, Reason :: term()}

              Unloads the OpenSSL engine given by Engine. An error tuple is
              returned if the engine can't be unloaded.

              The function raises a error:badarg if the parameter is in wrong
              format. It may also raise the exception error:notsup in case there
              is no engine support in the underlying OpenSSL implementation.

              See also the chapter Engine Load in the User's Guide.


       engine_by_id(EngineId) -> Result

              Types:

                 EngineId = unicode:chardata()
                 Result =
                     {ok, Engine :: engine_ref()} | {error, Reason :: term()}

              Get a reference to an already loaded engine with EngineId. An
              error tuple is returned if the engine can't be unloaded.

              The function raises a error:badarg if the parameter is in wrong
              format. It may also raise the exception error:notsup in case there
              is no engine support in the underlying OpenSSL implementation.

              See also the chapter Engine Load in the User's Guide.


       engine_ctrl_cmd_string(Engine, CmdName, CmdArg) -> Result

              Types:

                 Engine = term()
                 CmdName = CmdArg = unicode:chardata()
                 Result = ok | {error, Reason :: term()}

              Sends ctrl commands to the OpenSSL engine given by Engine. This
              function is the same as calling engine_ctrl_cmd_string/4 with
              Optional set to false.

              The function raises a error:badarg if the parameters are in wrong
              format. It may also raise the exception error:notsup in case there
              is no engine support in the underlying OpenSSL implementation.


       engine_ctrl_cmd_string(Engine, CmdName, CmdArg, Optional) ->
                                 Result

              Types:

                 Engine = term()
                 CmdName = CmdArg = unicode:chardata()
                 Optional = boolean()
                 Result = ok | {error, Reason :: term()}

              Sends ctrl commands to the OpenSSL engine given by Engine.
              Optional is a boolean argument that can relax the semantics of the
              function. If set to true it will only return failure if the ENGINE
              supported the given command name but failed while executing it, if
              the ENGINE doesn't support the command name it will simply return
              success without doing anything. In this case we assume the user is
              only supplying commands specific to the given ENGINE so we set
              this to false.

              The function raises a error:badarg if the parameters are in wrong
              format. It may also raise the exception error:notsup in case there
              is no engine support in the underlying OpenSSL implementation.


       engine_add(Engine) -> Result

              Types:

                 Engine = engine_ref()
                 Result = ok | {error, Reason :: term()}

              Add the engine to OpenSSL's internal list.

              The function raises a error:badarg if the parameters are in wrong
              format. It may also raise the exception error:notsup in case there
              is no engine support in the underlying OpenSSL implementation.


       engine_remove(Engine) -> Result

              Types:

                 Engine = engine_ref()
                 Result = ok | {error, Reason :: term()}

              Remove the engine from OpenSSL's internal list.

              The function raises a error:badarg if the parameters are in wrong
              format. It may also raise the exception error:notsup in case there
              is no engine support in the underlying OpenSSL implementation.


       engine_get_id(Engine) -> EngineId

              Types:

                 Engine = engine_ref()
                 EngineId = unicode:chardata()

              Return the ID for the engine, or an empty binary if there is no id
              set.

              The function raises a error:badarg if the parameters are in wrong
              format. It may also raise the exception error:notsup in case there
              is no engine support in the underlying OpenSSL implementation.


       engine_get_name(Engine) -> EngineName

              Types:

                 Engine = engine_ref()
                 EngineName = unicode:chardata()

              Return the name (eg a description) for the engine, or an empty
              binary if there is no name set.

              The function raises a error:badarg if the parameters are in wrong
              format. It may also raise the exception error:notsup in case there
              is no engine support in the underlying OpenSSL implementation.


       engine_list() -> Result

              Types:

                 Result = [EngineId :: unicode:chardata()]

              List the id's of all engines in OpenSSL's internal list.

              It may also raise the exception error:notsup in case there is no
              engine support in the underlying OpenSSL implementation.

              See also the chapter Engine Load in the User's Guide.

              May raise exception error:notsup in case engine functionality is
              not supported by the underlying OpenSSL implementation.


       ensure_engine_loaded(EngineId, LibPath) -> Result

              Types:

                 EngineId = LibPath = unicode:chardata()
                 Result =
                     {ok, Engine :: engine_ref()} | {error, Reason :: term()}

              Loads the OpenSSL engine given by EngineId and the path to the
              dynamic library implementing the engine. This function is the same
              as calling ensure_engine_loaded/3 with EngineMethods set to a list
              of all the possible methods. An error tuple is returned if the
              engine can't be loaded.

              The function raises a error:badarg if the parameters are in wrong
              format. It may also raise the exception error:notsup in case there
              is no engine support in the underlying OpenSSL implementation.

              See also the chapter Engine Load in the User's Guide.


       ensure_engine_loaded(EngineId, LibPath, EngineMethods) -> Result

              Types:

                 EngineId = LibPath = unicode:chardata()
                 EngineMethods = [engine_method_type()]
                 Result =
                     {ok, Engine :: engine_ref()} | {error, Reason :: term()}

              Loads the OpenSSL engine given by EngineId and the path to the
              dynamic library implementing the engine. This function differs
              from the normal engine_load in that sense it also add the engine
              id to the internal list in OpenSSL. Then in the following calls to
              the function it just fetch the reference to the engine instead of
              loading it again. An error tuple is returned if the engine can't
              be loaded.

              The function raises a error:badarg if the parameters are in wrong
              format. It may also raise the exception error:notsup in case there
              is no engine support in the underlying OpenSSL implementation.

              See also the chapter Engine Load in the User's Guide.


       ensure_engine_unloaded(Engine) -> Result

              Types:

                 Engine = engine_ref()
                 Result = ok | {error, Reason :: term()}

              Unloads an engine loaded with the ensure_engine_loaded function.
              It both removes the label from the OpenSSL internal engine list
              and unloads the engine. This function is the same as calling
              ensure_engine_unloaded/2 with EngineMethods set to a list of all
              the possible methods. An error tuple is returned if the engine
              can't be unloaded.

              The function raises a error:badarg if the parameters are in wrong
              format. It may also raise the exception error:notsup in case there
              is no engine support in the underlying OpenSSL implementation.

              See also the chapter Engine Load in the User's Guide.


       ensure_engine_unloaded(Engine, EngineMethods) -> Result

              Types:

                 Engine = engine_ref()
                 EngineMethods = [engine_method_type()]
                 Result = ok | {error, Reason :: term()}

              Unloads an engine loaded with the ensure_engine_loaded function.
              It both removes the label from the OpenSSL internal engine list
              and unloads the engine. An error tuple is returned if the engine
              can't be unloaded.

              The function raises a error:badarg if the parameters are in wrong
              format. It may also raise the exception error:notsup in case there
              is no engine support in the underlying OpenSSL implementation.

              See also the chapter Engine Load in the User's Guide.



Ericsson AB                        crypto 4.4                       crypto(3erl)