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60 lines
1.5 KiB
60 lines
1.5 KiB
package pkcs8 |
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import ( |
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"bytes" |
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"crypto/cipher" |
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"encoding/asn1" |
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) |
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type cipherWithBlock struct { |
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oid asn1.ObjectIdentifier |
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ivSize int |
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keySize int |
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newBlock func(key []byte) (cipher.Block, error) |
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} |
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func (c cipherWithBlock) IVSize() int { |
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return c.ivSize |
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} |
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func (c cipherWithBlock) KeySize() int { |
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return c.keySize |
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} |
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func (c cipherWithBlock) OID() asn1.ObjectIdentifier { |
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return c.oid |
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} |
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func (c cipherWithBlock) Encrypt(key, iv, plaintext []byte) ([]byte, error) { |
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block, err := c.newBlock(key) |
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if err != nil { |
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return nil, err |
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} |
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return cbcEncrypt(block, key, iv, plaintext) |
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} |
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func (c cipherWithBlock) Decrypt(key, iv, ciphertext []byte) ([]byte, error) { |
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block, err := c.newBlock(key) |
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if err != nil { |
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return nil, err |
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} |
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return cbcDecrypt(block, key, iv, ciphertext) |
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} |
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func cbcEncrypt(block cipher.Block, key, iv, plaintext []byte) ([]byte, error) { |
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mode := cipher.NewCBCEncrypter(block, iv) |
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paddingLen := block.BlockSize() - (len(plaintext) % block.BlockSize()) |
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ciphertext := make([]byte, len(plaintext)+paddingLen) |
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copy(ciphertext, plaintext) |
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copy(ciphertext[len(plaintext):], bytes.Repeat([]byte{byte(paddingLen)}, paddingLen)) |
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mode.CryptBlocks(ciphertext, ciphertext) |
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return ciphertext, nil |
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} |
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func cbcDecrypt(block cipher.Block, key, iv, ciphertext []byte) ([]byte, error) { |
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mode := cipher.NewCBCDecrypter(block, iv) |
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plaintext := make([]byte, len(ciphertext)) |
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mode.CryptBlocks(plaintext, ciphertext) |
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// TODO: remove padding |
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return plaintext, nil |
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}
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