Generate Rsa Public Key From Modulus Exponent
15.04.2020by admin
RSA is the most widespread and used public key algorithm. Its security isbased on the difficulty of factoring large integers. The algorithm haswithstood attacks for more than 30 years, and it is therefore consideredreasonably secure for new designs.
The algorithm can be used for both confidentiality (encryption) andauthentication (digital signature). It is worth noting that signing anddecryption are significantly slower than verification and encryption.
- Apr 06, 2020 I fixed this by base64-encoding the exponent and modulus in big-endian format (in python) and then loading them with RSACryptoServiceProvider.FromXmlString (in.NET). Working Example. I hardcoded the (N, E, D) parameters for a private key in python and exported the exponent and modulus to be used later for encryption.
- Being this an RSA key the fields represent specific components of the algorithm. We find in order the modulus n = pq, the public exponent e, the private exponent d, the two prime numbers p and q, and the values dp, dq, and qinv (for the Chinese remainder theorem speed-up).
- I have a RSA private key with modulus m, public exponent e and private exponent d, but the program I am using needs the modulus's prime factors p and q. Is it possible to use e and d to get p and q?
The cryptographic strength is primarily linked to the length of the RSA modulus n.In 2017, a sufficient length is deemed to be 2048 bits. For more information,see the most recent ECRYPT report.
It's the length of the modulus used to compute the RSA key pair. The public key is made of modulus and public exponent, while the private key is made of modulus and private exponent. but the online tools for generating RSA key pairs have different lengths output!
Both RSA ciphertexts and RSA signatures are as large as the RSA modulus n (256bytes if n is 2048 bit long).
The module Crypto.PublicKey.RSA provides facilities for generating new RSA keys,reconstructing them from known components, exporting them, and importing them.
As an example, this is how you generate a new RSA key pair, save it in a filecalled mykey.pem, and then read it back:
Crypto.PublicKey.RSA.generate(bits, randfunc=None, e=65537)¶Create a new RSA key pair.
The algorithm closely follows NIST FIPS 186-4 in itssections B.3.1 and B.3.3. The modulus is the product oftwo non-strong probable primes.Each prime passes a suitable number of Miller-Rabin testswith random bases and a single Lucas test.
| Parameters: |
|
|---|
Returns: an RSA key object (RsaKey, with private key).
Crypto.PublicKey.RSA.construct(rsa_components, consistency_check=True)¶Construct an RSA key from a tuple of valid RSA components.
The modulus n must be the product of two primes.The public exponent e must be odd and larger than 1.
This special offer gives you full member access to our downloads. DownloadKeeper.com provides 24/7 fast download access to the most recent releases. We currently have 355,740 direct downloads including categories such as: software, movies, games, tv, adult movies, music, ebooks, apps and much more. Homeworld 2 cd-key generator. Our members download database is updated on a daily basis.Take advantage of our limited time offer and gain access to unlimited downloads for FREE! That's how much we trust our unbeatable service.
In case of a private key, the following equations must apply:
[begin{split}begin{align}p*q &= n e*d &equiv 1 ( text{mod lcm} [(p-1)(q-1)]) p*u &equiv 1 ( text{mod } q)end{align}end{split}]
| Parameters: |
|
|---|---|
| Raises: |
|
Returns: An RSA key object (RsaKey).
Crypto.PublicKey.RSA.import_key(extern_key, passphrase=None)¶Import an RSA key (public or private).
| Parameters: |
|
|---|
Returns: An RSA key object (RsaKey).
| Raises: | ValueError/IndexError/TypeError – When the given key cannot be parsed (possibly because the passphrase is wrong). |
|---|
Crypto.PublicKey.RSA.RsaKey(**kwargs)¶Class defining an actual RSA key.Do not instantiate directly.Use generate(), construct() or import_key() instead.
| Variables: |
|
|---|
exportKey(format='PEM', passphrase=None, pkcs=1, protection=None, randfunc=None)¶Export this RSA key.
| Parameters: |
|
|---|---|
| Returns: | the encoded key |
| Return type: | byte string |
| Raises: |
|
Warning
If you don’t provide a pass phrase, the private key will beexported in the clear!
export_key(format='PEM', passphrase=None, pkcs=1, protection=None, randfunc=None)¶Export this RSA key.
| Parameters: |
|
|---|---|
| Returns: | the encoded key |
| Return type: | byte string |
| Raises: |
|
Warning
If you don’t provide a pass phrase, the private key will beexported in the clear!
has_private()¶Whether this is an RSA private key
publickey()¶A matching RSA public key.
| Returns: | a new RsaKey object |
|---|
size_in_bits()¶Size of the RSA modulus in bits
size_in_bytes()¶The minimal amount of bytes that can hold the RSA modulus
Generate Rsa Public Key From Modulus Exponent In Math
Crypto.PublicKey.RSA.oid = '1.2.840.113549.1.1.1'¶Object ID for the RSA encryption algorithm. This OID often indicatesa generic RSA key, even when such key will be actually used for digitalsignatures.
Takes a RSA public key modulus and exponent in base64 encoding and produces a public key file in PEM format
Makefile
| CC = clang |
| CFLAGS = |
| DEPS = |
| OBJ = modexp2pubkey.o |
| LIBS = -lssl -lcrypto |
| %.o: %.c $(DEPS) |
| $(CC) -c -o $@$<$(CFLAGS) |
| modexp2pubkey: $(OBJ) |
| $(CC) -o $@$^$(CFLAGS)$(LIBS) |
| .PHONY: clean |
| clean: |
| rm -f *.o |
modexp2pubkey.c
| #include<string.h> |
| #include<openssl/rsa.h> |
| #include<openssl/evp.h> |
| #include<openssl/bn.h> |
| #include<openssl/pem.h> |
| // cheating, . ignoring deprecation warnings |
| #pragma GCC diagnostic ignored '-Wdeprecated-declarations' |
| unsignedchar *base64_decode(constchar* base64data, int* len) { |
| BIO *b64, *bmem; |
| size_t length = strlen(base64data); |
| unsignedchar *buffer = (unsignedchar *)malloc(length); |
| b64 = BIO_new(BIO_f_base64()); |
| BIO_set_flags(b64, BIO_FLAGS_BASE64_NO_NL); |
| bmem = BIO_new_mem_buf((void*)base64data, length); |
| bmem = BIO_push(b64, bmem); |
| *len = BIO_read(bmem, buffer, length); |
| BIO_free_all(bmem); |
| return buffer; |
| } |
| BIGNUM* bignum_base64_decode(constchar* base64bignum) { |
| BIGNUM* bn = NULL; |
| int len; |
| unsignedchar* data = base64_decode(base64bignum, &len); |
| if (len) { |
| bn = BN_bin2bn(data, len, NULL); |
| } |
| free(data); |
| return bn; |
| } |
| EVP_PKEY* RSA_fromBase64(constchar* modulus_b64, constchar* exp_b64) { |
| BIGNUM *n = bignum_base64_decode(modulus_b64); |
| BIGNUM *e = bignum_base64_decode(exp_b64); |
| if (!n) printf('Invalid encoding for modulusn'); |
| if (!e) printf('Invalid encoding for public exponentn'); |
| if (e && n) { |
| EVP_PKEY* pRsaKey = EVP_PKEY_new(); |
| RSA* rsa = RSA_new(); |
| rsa->e = e; |
| rsa->n = n; |
| EVP_PKEY_assign_RSA(pRsaKey, rsa); |
| return pRsaKey; |
| } else { |
| if (n) BN_free(n); |
| if (e) BN_free(e); |
| returnNULL; |
| } |
| } |
| voidassert_syntax(int argc, char** argv) { |
| if (argc != 4) { |
| fprintf(stderr, 'Description: %s takes a RSA public key modulus and exponent in base64 encoding and produces a public key file in PEM format.n', argv[0]); |
| fprintf(stderr, 'syntax: %s <modulus_base64> <exp_base64> <output_file>n', argv[0]); |
| exit(1); |
| } |
| } |
| intmain(int argc, char** argv) { |
| assert_syntax(argc, argv); |
| constchar* modulus = argv[1]; |
| constchar* exp = argv[2]; |
| constchar* filename = argv[3]; |
| EVP_PKEY* pkey = RSA_fromBase64(modulus, exp); |
| if (pkey NULL) { |
| fprintf(stderr, 'an error occurred :(n'); |
| return2; |
| } else { |
| printf('success decoded into RSA public keyn'); |
| FILE* file = fopen(filename, 'w'); |
| PEM_write_PUBKEY(file, pkey); |
| fflush(file); |
| fclose(file); |
| printf('written to file: %sn', filename); |
| } |
| return0; |
| } |
Openssl Modulus
Sign up for freeto join this conversation on GitHub. Already have an account? Sign in to comment
Comments are closed.