bcrypt

Package bcrypt implements Provos and Mazières's bcrypt adaptive hashing algorithm. See http://www.usenix.org/event/usenix99/provos/provos.pdf

Usage

Example

var password = "pass123"
var salt = "faf6132ae848fkjf" // 16 byte!

passHash, err := GenerateFromPasswordAndSalt([]byte(password), cost, []byte(salt))
if err != nil {
	log.Fatalf(
		"Error when generating hash for password %s with salst %s, cost=%d: %v"
	    password, salt, cost, err,
	)
}

if err := CompareHashAndPassword(passHash, []byte(password)); err != nil {
	log.Fatalf("can't compare hash %s ans password %s: %v", string(passHash), password, err)
}

Constants

const (
	MinCost     int = 4  // the minimum allowable cost as passed in to GenerateFromPassword
	MaxCost     int = 31 // the maximum allowable cost as passed in to GenerateFromPassword
	DefaultCost int = 10 // the cost that will actually be set if a cost below MinCost is passed into GenerateFromPassword
)

Globals (errors)

var ErrHashTooShort = errors.New("crypto/bcrypt: hashedSecret too short to be a bcrypted password")

ErrHashTooShort is the error returned from CompareHashAndPassword when a hash is too short to be a bcrypt hash.

var ErrMismatchedHashAndPassword = errors.New("crypto/bcrypt: hashedPassword is not the hash of the given password")

ErrMismatchedHashAndPassword is the error returned from CompareHashAndPassword when a password and hash do not match.

Functions

func CompareHashAndPassword

func CompareHashAndPassword(hashedPassword, password []byte) error

CompareHashAndPassword compares a bcrypt hashed password with its possible plaintext equivalent. Returns nil on success, or an error on failure.

func Cost

func Cost(hashedPassword []byte) (int, error)

Cost returns the hashing cost used to create the given hashed password. When, in the future, the hashing cost of a password system needs to be increased in order to adjust for greater computational power, this function allows one to establish which passwords need to be updated.

func GenerateFromPassword

func GenerateFromPassword(password []byte, cost int) ([]byte, error)

GenerateFromPassword returns the bcrypt hash of the password at the given cost. If the cost given is less than MinCost, the cost will be set to DefaultCost, instead. Use CompareHashAndPassword, as defined in this package, to compare the returned hashed password with its cleartext version.

func GenerateFromPasswordAndSalt

func GenerateFromPasswordAndSalt(password []byte, cost int, salt []byte) ([]byte, error)

GenerateFromPasswordAndSalt lets generate hash from password, cost (number of rounds) and 16 bytes of a salt.

type HashVersionTooNewError

type HashVersionTooNewError byte

HashVersionTooNewError is the error returned from CompareHashAndPassword when a hash was/created with a bcrypt algorithm newer than this implementation.

func (HashVersionTooNewError) Error

func (hv HashVersionTooNewError) Error() string

type InvalidCostError

type InvalidCostError int

func (InvalidCostError) Error

func (ic InvalidCostError) Error() string

type InvalidHashPrefixError

type InvalidHashPrefixError byte

InvalidHashPrefixError is the error returned from CompareHashAndPassword when a hash starts with something other than '$'

func (InvalidHashPrefixError) Error

func (ih InvalidHashPrefixError) Error() string

xorium/gobcrypto