rc5.go

package rc5

import (
    "fmt"
    "strconv"
    "crypto/cipher"

    "github.com/deatil/go-cryptobin/tool/alias"
)

// KeySizeError
type KeySizeError int

func (k KeySizeError) Error() string {
    return "cryptobin/rc5: invalid key size " + strconv.Itoa(int(k))
}

// Reference: https://en.wikipedia.org/wiki/RC5
// http://people.csail.mit.edu/rivest/Rivest-rc5rev.pdf

// NewCipher creates and returns a new cipher.Block.
// The key argument should be the RC5 key, the wordSize arguement should be word size in bits,
// the r argument should be number of rounds.
func NewCipher(key []byte, wordSize, r uint) (cipher.Block, error) {
    k := len(key)
    switch k {
        case 8, 16, 24, 32:
            break
        default:
            return nil, fmt.Errorf("cryptobin/rc5: invalid key size %d, we support 16/24/32 now", k)
    }

    if r < 8 || r > 127 {
        return nil, fmt.Errorf("cryptobin/rc5: invalid rounds %d, should be between 8 and 127", r)
    }

    switch wordSize {
        case 16:
            return newCipher16(key, r)
        case 32:
            return newCipher32(key, r)
        case 64:
            return newCipher64(key, r)
        default:
            return nil, fmt.Errorf("cryptobin/rc5: unsupported word size %d, support 16/32/64 now", wordSize)
    }
}

// NewCipher16 creates and returns a new cipher.Block with 16 bits word size.
// The key argument should be the RC5 key, the r argument should be number of rounds.
func NewCipher16(key []byte, r uint) (cipher.Block, error) {
    return NewCipher(key, 16, r)
}

// NewCipher32 creates and returns a new cipher.Block with 32 bits word size.
// The key argument should be the RC5 key, the r argument should be number of rounds.
func NewCipher32(key []byte, r uint) (cipher.Block, error) {
    return NewCipher(key, 32, r)
}

// NewCipher64 creates and returns a new cipher.Block with 64 bits word size.
// The key argument should be the RC5 key, the r argument should be number of rounds.
func NewCipher64(key []byte, r uint) (cipher.Block, error) {
    return NewCipher(key, 64, r)
}

var inexactOverlap = alias.InexactOverlap