Package

The crypto package provides cryptographic primitives built on OpenSSL:

• One-shot hash functions (MD5, SHA256, etc.) and streaming digests (Digest)
• HMAC message authentication (HmacSha256)
• PBKDF2 key derivation (Pbkdf2Sha256)
• Cryptographically secure random bytes (RandBytes)
• Constant-time comparison (ConstantTimeCompare)

When a call can fail

A call here gives back a correct result or it raises. It never gives back an incorrect one, so there is no value to check for and no sentinel to compare against.

The Digest constructors, Digest.append, Digest.final, HmacSha256, Pbkdf2Sha256 and RandBytes are partial. They raise when OpenSSL could not do what was asked of it. Constructing a Digest raises when OpenSSL cannot give it a context. HmacSha256, Pbkdf2Sha256 and RandBytes also raise when a length you gave them is larger than the C int OpenSSL takes for it.

The one-shot hash functions and ConstantTimeCompare cannot fail and are total.

When HmacSha256 raises, reject the message. Do not compare it against a code of your own making — a code you invent is one an attacker can send you.

Public Types

• primitive ConstantTimeCompare
• class Digest
• interface HashFn
• primitive HmacSha256
• primitive MD4
• primitive MD5
• primitive Pbkdf2Sha256
• primitive RIPEMD160
• primitive RandBytes
• primitive SHA1
• primitive SHA224
• primitive SHA256
• primitive SHA384
• primitive SHA512
• primitive ToHexString