Package M2Crypto :: Module DSA :: Class DSA

Class DSA

This class is a context supporting DSA key and parameter values, signing and verifying.

Simple example:

   from M2Crypto import EVP, DSA, util
   
   message = 'Kilroy was here!'
   md = EVP.MessageDigest('sha1')
   md.update(message)        
   digest = md.final()
   
   dsa = DSA.gen_params(1024)
   dsa.gen_key()
   r, s = dsa.sign(digest)
   good = dsa.verify(digest, r, s)
   if good:
       print '  ** success **'
   else:
       print '  ** verification failed **'

Instance Methods

m2_dsa_free(...)

__init__(self, dsa, _pyfree=0)
Use one of the factory functions to create an instance.

__del__(self)

int

__len__(self)
Return the key length.

str

__getattr__(self, name)
Return specified DSA parameters and key values.

__setattr__(self, name, value)

set_params(self, p, q, g)
Set new parameters.

gen_key(self)
Generate a key pair.

save_params(self, filename)
Save the DSA parameters to a file.

save_params_bio(self, bio)
Save DSA parameters to a BIO object.

save_key(self, filename, cipher='aes_128_cbc', callback=<function passphrase_callback at 0x83b2a04>)
Save the DSA key pair to a file.

save_key_bio(self, bio, cipher='aes_128_cbc', callback=<function passphrase_callback at 0x83b2a04>)
Save DSA key pair to a BIO object.

save_pub_key(self, filename)
Save the DSA public key (with parameters) to a file.

save_pub_key_bio(self, bio)
Save DSA public key (with parameters) to a BIO object.

tuple

sign(self, digest)
Sign the digest.

int

verify(self, digest, r, s)
Verify a newly calculated digest against the signature values r and s.

sign_asn1(self, digest)

verify_asn1(self, digest, blob)

int

check_key(self)
Check to be sure the DSA object has a valid private key.

Method Details

len(self)
(Length operator)

Return the key length.

Returns: int: the DSA key length in bits

getattr(self, name)
(Qualification operator)

Return specified DSA parameters and key values.

Parameters:

name (str) - name of variable to be returned. Must be one of 'p', 'q', 'g', 'pub', 'priv'.

Returns: str

value of specified variable (a "byte string")

set_params(self, p, q, g)

Set new parameters.

Warning: This does not change the private key, so it may be unsafe to use this method. It is better to use gen_params function to create a new DSA object.

save_params(self, filename)

Save the DSA parameters to a file.

Parameters:

filename (str) - Save the DSA parameters to this file.

Returns:

1 (true) if successful

save_params_bio(self, bio)

Save DSA parameters to a BIO object.

Parameters:

bio (M2Crypto.BIO object) - Save DSA parameters to this object.

Returns:

1 (true) if successful

save_key(self, filename, cipher=`'aes_128_cbc'`, callback=<function passphrase_callback at 0x83b2a04>)

Save the DSA key pair to a file.

Parameters:

filename (str) - Save the DSA key pair to this file.
cipher (str) - name of symmetric key algorithm and mode to encrypt the private key.

Returns:

1 (true) if successful

save_key_bio(self, bio, cipher=`'aes_128_cbc'`, callback=<function passphrase_callback at 0x83b2a04>)

Save DSA key pair to a BIO object.

Parameters:

bio (M2Crypto.BIO object) - Save DSA parameters to this object.
cipher (str) - name of symmetric key algorithm and mode to encrypt the private key.

Returns:

1 (true) if successful

save_pub_key(self, filename)

Save the DSA public key (with parameters) to a file.

Parameters:

filename (str) - Save DSA public key (with parameters) to this file.

Returns:

1 (true) if successful

save_pub_key_bio(self, bio)

Save DSA public key (with parameters) to a BIO object.

Parameters:

bio (M2Crypto.BIO object) - Save DSA public key (with parameters) to this object.

Returns:

1 (true) if successful

sign(self, digest)

Sign the digest.

Parameters:

digest (str) - SHA-1 hash of message (same as output from MessageDigest, a "byte string")

Returns: tuple

DSA signature, a tuple of two values, r and s, both "byte strings".

verify(self, digest, r, s)

Verify a newly calculated digest against the signature values r and s.

Parameters:

digest (str) - SHA-1 hash of message (same as output from MessageDigest, a "byte string")
r (str) - r value of the signature, a "byte string"
s (str) - s value of the signature, a "byte string"

Returns: int

1 (true) if verify succeeded, 0 if failed

check_key(self)

Check to be sure the DSA object has a valid private key.

Returns: int: 1 (true) if a valid private key

Class DSA

__len__(self) (Length operator)

__getattr__(self, name) (Qualification operator)

set_params(self, p, q, g)

save_params(self, filename)

save_params_bio(self, bio)

save_key(self, filename, cipher='aes_128_cbc', callback=<function passphrase_callback at 0x83b2a04>)

save_key_bio(self, bio, cipher='aes_128_cbc', callback=<function passphrase_callback at 0x83b2a04>)

save_pub_key(self, filename)

save_pub_key_bio(self, bio)

sign(self, digest)

verify(self, digest, r, s)

check_key(self)

len(self)
(Length operator)

getattr(self, name)
(Qualification operator)

save_key(self, filename, cipher=`'aes_128_cbc'`, callback=<function passphrase_callback at 0x83b2a04>)

save_key_bio(self, bio, cipher=`'aes_128_cbc'`, callback=<function passphrase_callback at 0x83b2a04>)