string_hash -- Returns a 64-character hexadecimal string. binary_hash -- Returns a 64-character hexadecimal string.
Returns a 64-character hexadecimal string encoding the result of applying the SHA256 cryptographically secure hash function to the contents of the string text or the binary string bin-string. If algo is provided, it specifies the hashing algorithm to use. "MD5", "SHA1" and "SHA256" are all supported.
Note that the MD5 hash algorithm is broken from a cryptographic standpoint, as is SHA1. Both are included for interoperability with existing applications (both are still popular).
All supported hash functions have the property that, if
string_hash(x) == string_hash(y)
then, almost certainly,
equal(x, y)
This can be useful, for example, in certain networking applications: after sending a large piece of text across a connection, also send the result of applying string_hash() to the text; if the destination site also applies string_hash() to the text and gets the same result, you can be quite confident that the large text has arrived unchanged.