s2k

Documentation

Overview

Package s2k implements the various OpenPGP string-to-key transforms as specified in RFC 4800 section 3.7.1.

Index

• func HashIdToHash(id byte) (h crypto.Hash, ok bool)
• func HashIdToString(id byte) (name string, ok bool)
• func HashToHashId(h crypto.Hash) (id byte, ok bool)
• func Iterated(out []byte, h hash.Hash, in []byte, salt []byte, count int)
• func Parse(r io.Reader) (f func(out, in []byte), keyIsMissing bool, err error)
• func Salted(out []byte, h hash.Hash, in []byte, salt []byte)
• func Serialize(w io.Writer, key []byte, rand io.Reader, passphrase []byte, c *Config) error
• func Simple(out []byte, h hash.Hash, in []byte)
• type Config

Functions

func HashIdToHash

func HashIdToHash(id byte) (h crypto.Hash, ok bool)

HashIdToHash returns a crypto.Hash which corresponds to the given OpenPGP hash id.

func HashIdToString

func HashIdToString(id byte) (name string, ok bool)

HashIdToString returns the name of the hash function corresponding to the given OpenPGP hash id.

func HashToHashId

func HashToHashId(h crypto.Hash) (id byte, ok bool)

HashIdToHash returns an OpenPGP hash id which corresponds the given Hash.

func Iterated

func Iterated(out []byte, h hash.Hash, in []byte, salt []byte, count int)

Iterated writes to out the result of computing the Iterated and Salted S2K function (RFC 4880, section 3.7.1.3) using the given hash, input passphrase, salt and iteration count.

func Parse

func Parse(r io.Reader) (f func(out, in []byte), keyIsMissing bool, err error)

Parse reads a binary specification for a string-to-key transformation from r. It returns either:

nil, false, err — on error.
nil, true, nil  — if the S2K is a special GNU extension that indicates that
                  the private key is missing.
f, false, nil   — f is a function that performs the S2K transformation.

func Salted

func Salted(out []byte, h hash.Hash, in []byte, salt []byte)

Salted writes to out the result of computing the Salted S2K function (RFC 4880, section 3.7.1.2) using the given hash, input passphrase and salt.

func Serialize

func Serialize(w io.Writer, key []byte, rand io.Reader, passphrase []byte, c *Config) error

Serialize salts and stretches the given passphrase and writes the resulting key into key. It also serializes an S2K descriptor to w. The key stretching can be configured with c, which may be nil. In that case, sensible defaults will be used.

func Simple

func Simple(out []byte, h hash.Hash, in []byte)

Simple writes to out the result of computing the Simple S2K function (RFC 4880, section 3.7.1.1) using the given hash and input passphrase.

Types

type Config

type Config struct {
	// Hash is the default hash function to be used. If
	// nil, SHA1 is used.
	Hash crypto.Hash
	// S2KCount is only used for symmetric encryption. It
	// determines the strength of the passphrase stretching when
	// the said passphrase is hashed to produce a key. S2KCount
	// should be between 1024 and 65011712, inclusive. If Config
	// is nil or S2KCount is 0, the value 65536 used. Not all
	// values in the above range can be represented. S2KCount will
	// be rounded up to the next representable value if it cannot
	// be encoded exactly. When set, it is strongly encrouraged to
	// use a value that is at least 65536. See RFC 4880 Section
	// 3.7.1.3.
	S2KCount int
}

Config collects configuration parameters for s2k key-stretching transformatioms. A nil *Config is valid and results in all default values. Currently, Config is used only by the Serialize function in this package.