- Generate Rsa Public Key From Modulus Exponent C In Excel
- Create Rsa Public Key From Modulus And Exponent
Takes a RSA public key modulus and exponent in base64 encoding and produces a public key file in PEM format
Was trying to generate a RSA public key with RSA modulus(n) and RSA public exponent(e). I have tried to use SCZ-BasicEncodingRules-iOS, but unfortunately SCZ-BasicEncodingRules-iOS has wrong decoding algorithm for iOS 8 and above. Feb 13, 2014 node-rsa-pem-from-mod-exp. Create RSA Public Key PEM from Modulus and Exponent value in node.js.There are no dependencies to other modules for use. This allows you to use the modulus/exponent values for validating signed value.
Makefile
- C (Cpp) vb2publickeyfree - 3 examples found. These are the top rated real world C (Cpp) examples of vb2publickeyfree extracted from open source projects. You can rate examples to help us improve the quality of examples.
- RSA (Rivest–Shamir–Adleman) is one of the first public-key cryptosystems and is widely used for secure data transmission. In such a cryptosystem, the encryption key is public and distinct from the decryption key which is kept secret (private). In RSA, this asymmetry is based on the practical difficulty of factoring the product of two large prime numbers, the 'factoring problem'.
- How to generate public/private key in C#. Asymmetric cryptography also known as public-key encryption uses a public/private key pair to encrypt and decrypt data. In.NET, the RSACryptoServiceProvider and DSACryptoServiceProvider classes are used for asymmetric encryption.
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; |
} |
Sign up for freeto join this conversation on GitHub. Already have an account? Sign in to comment
-->Definition
Represents the standard parameters for the RSA algorithm.
RSAParameters
- Attributes
Remarks
The RSA class exposes an ExportParameters method that enables you to retrieve the raw RSA key in the form of an RSAParameters structure. Understanding the contents of this structure requires familiarity with how the RSA algorithm works. The next section discusses the algorithm briefly.
RSA Algorithm
To generate a key pair, you start by creating two large prime numbers named p and q. These numbers are multiplied and the result is called n. Because p and q are both prime numbers, the only factors of n are 1, p, q, and n.
If we consider only numbers that are less than n, the count of numbers that are relatively prime to n, that is, have no factors in common with n, equals (p - 1)(q - 1).
Now you choose a number e, which is relatively prime to the value you calculated. The public key is now represented as {e, n}.
To create the private key, you must calculate d, which is a number such that (d)(e) mod (p - 1)(q - 1) = 1. In accordance with the Euclidean algorithm, the private key is now {d, n}.
Encryption of plaintext m to ciphertext c is defined as c = (m ^ e) mod n. Decryption would then be defined as m = (c ^ d) mod n.
Summary of Fields
Section A.1.2 of the PKCS #1: RSA Cryptography Standard on the RSA Laboratories Web site defines a format for RSA private keys.
![Generate Rsa Public Key From Modulus Exponent C Generate Rsa Public Key From Modulus Exponent C](/uploads/1/2/6/8/126886724/614546067.png)
The following table summarizes the fields of the RSAParameters structure. The third column provides the corresponding field in section A.1.2 of PKCS #1: RSA Cryptography Standard.
RSAParameters field | Contains | Corresponding PKCS #1 field |
---|---|---|
D | d, the private exponent | privateExponent |
DP | d mod (p - 1) | exponent1 |
DQ | d mod (q - 1) | exponent2 |
Exponent | e, the public exponent | publicExponent |
InverseQ | (InverseQ)(q) = 1 mod p | coefficient |
Modulus | n | modulus |
P | p | prime1 |
Q | q | prime2 |
The security of RSA derives from the fact that, given the public key { e, n }, it is computationally infeasible to calculate d, either directly or by factoring n into p and q. Therefore, any part of the key related to d, p, or q must be kept secret. If you call
ExportParameters and ask for only the public key information, this is why you will receive only Exponent and Modulus. The other fields are available only if you have access to the private key, and you request it.
Generate a key for steam uplay. RSAParameters is not encrypted in any way, so you must be careful when you use it with the private key information. In fact, none of the fields that contain private key information can be serialized. If you try to serialize an RSAParameters structure with a remoting call or by using one of the serializers, you will receive only public key information. If you want to pass private key information, you will have to manually send that data. In all cases, if anyone can derive the parameters, the key that you transmit becomes useless.
.NET Core 2.1.0 and later: The serialization restrictions have been removed and all members of RSAParameters are serialized. Care must be excercised when writing or upgrading code against .NET Core 2.1.0 or later, because if anyone can derive or intercept the private key parameters the key and all the information encrypted or signed with it are compromised.
Fields
Generate Rsa Public Key From Modulus Exponent C In Excel
D | Represents the D parameter for the RSA algorithm. |
DP | Represents the DP parameter for the RSA algorithm. |
DQ | Represents the DQ parameter for the RSA algorithm. |
Exponent | Represents the Exponent parameter for the RSA algorithm. |
InverseQ | Represents the InverseQ parameter for the RSA algorithm. |
Modulus | Represents the Modulus parameter for the RSA algorithm. |
P | Represents the P parameter for the RSA algorithm. |
Q | Represents the Q parameter for the RSA algorithm. |