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84 lines
2.6 KiB
84 lines
2.6 KiB
"""ASN1 encoding helpers for converting between PKCS1 and PKCS8.
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Required by rsa_backend but not cryptography_backend.
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"""
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from pyasn1.codec.der import decoder, encoder
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from pyasn1.type import namedtype, univ
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RSA_ENCRYPTION_ASN1_OID = "1.2.840.113549.1.1.1"
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class RsaAlgorithmIdentifier(univ.Sequence):
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"""ASN1 structure for recording RSA PrivateKeyAlgorithm identifiers."""
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componentType = namedtype.NamedTypes(
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namedtype.NamedType("rsaEncryption", univ.ObjectIdentifier()), namedtype.NamedType("parameters", univ.Null())
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)
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class PKCS8PrivateKey(univ.Sequence):
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"""ASN1 structure for recording PKCS8 private keys."""
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componentType = namedtype.NamedTypes(
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namedtype.NamedType("version", univ.Integer()),
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namedtype.NamedType("privateKeyAlgorithm", RsaAlgorithmIdentifier()),
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namedtype.NamedType("privateKey", univ.OctetString()),
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)
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class PublicKeyInfo(univ.Sequence):
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"""ASN1 structure for recording PKCS8 public keys."""
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componentType = namedtype.NamedTypes(
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namedtype.NamedType("algorithm", RsaAlgorithmIdentifier()), namedtype.NamedType("publicKey", univ.BitString())
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)
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def rsa_private_key_pkcs8_to_pkcs1(pkcs8_key):
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"""Convert a PKCS8-encoded RSA private key to PKCS1."""
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decoded_values = decoder.decode(pkcs8_key, asn1Spec=PKCS8PrivateKey())
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try:
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decoded_key = decoded_values[0]
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except IndexError:
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raise ValueError("Invalid private key encoding")
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return decoded_key["privateKey"]
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def rsa_private_key_pkcs1_to_pkcs8(pkcs1_key):
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"""Convert a PKCS1-encoded RSA private key to PKCS8."""
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algorithm = RsaAlgorithmIdentifier()
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algorithm["rsaEncryption"] = RSA_ENCRYPTION_ASN1_OID
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pkcs8_key = PKCS8PrivateKey()
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pkcs8_key["version"] = 0
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pkcs8_key["privateKeyAlgorithm"] = algorithm
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pkcs8_key["privateKey"] = pkcs1_key
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return encoder.encode(pkcs8_key)
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def rsa_public_key_pkcs1_to_pkcs8(pkcs1_key):
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"""Convert a PKCS1-encoded RSA private key to PKCS8."""
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algorithm = RsaAlgorithmIdentifier()
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algorithm["rsaEncryption"] = RSA_ENCRYPTION_ASN1_OID
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pkcs8_key = PublicKeyInfo()
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pkcs8_key["algorithm"] = algorithm
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pkcs8_key["publicKey"] = univ.BitString.fromOctetString(pkcs1_key)
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return encoder.encode(pkcs8_key)
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def rsa_public_key_pkcs8_to_pkcs1(pkcs8_key):
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"""Convert a PKCS8-encoded RSA private key to PKCS1."""
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decoded_values = decoder.decode(pkcs8_key, asn1Spec=PublicKeyInfo())
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try:
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decoded_key = decoded_values[0]
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except IndexError:
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raise ValueError("Invalid public key encoding.")
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return decoded_key["publicKey"].asOctets()
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