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Version: v7.1.0

crypto_data_hash/3

Description​

crypto_data_hash/3 is a predicate that computes the Hash of the given Data using different algorithms.

The signature is as follows:

crypto_data_hash(+Data, -Hash, +Options) is det
crypto_data_hash(+Data, +Hash, +Options) is det

Where:

  • Data represents the data to be hashed, given as an atom, or code-list.
  • Hash represents the Hashed value of Data, which can be given as an atom or a variable.
  • Options are additional configurations for the hashing process. Supported options include: encoding(+Format) which specifies the encoding used for the Data, and algorithm(+Alg) which chooses the hashing algorithm among the supported ones (see below for details).

For Format, the supported encodings are:

  • utf8 (default), the UTF-8 encoding represented as an atom.
  • text, the plain text encoding represented as an atom.
  • hex, the hexadecimal encoding represented as an atom.
  • octet, the raw byte encoding depicted as a list of integers ranging from 0 to 255.

For Alg, the supported algorithms are:

  • sha256 (default): The SHA-256 algorithm.
  • sha512: The SHA-512 algorithm.
  • md5: (insecure) The MD5 algorithm.

Note: Due to the principles of the hash algorithm (pre-image resistance), this predicate can only compute the hash value from input data, and cannot compute the original input data from the hash value.

Examples​

# Compute the SHA-256 hash of the given data and unify it with the given Hash.
- crypto_data_hash('Hello OKP4', Hash).

# Compute the SHA-256 hash of the given hexadecimal data and unify it with the given Hash.
- crypto_data_hash('9b038f8ef6918cbb56040dfda401b56b...', Hash, encoding(hex)).

# Compute the SHA-256 hash of the given hexadecimal data and unify it with the given Hash.
- crypto_data_hash([127, ...], Hash, encoding(octet)).