- 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.
- Generates a RSA public key with given modulus and public/private exponent: RSA « Security « Android.
- @fjsj it's good to use Base64 encoding to encode a byte sequence to a string instead of Unicode encoding, because not every byte sequence has a Unicode representation. In this example, when the RSA encrypts the input bytes you can't be sure if the output bytes have a Unicode representation, but you can be sure that they have a Base64 representation.
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It works with legacy keys on traditional servers as well as dynamic andkeyless elastic environments in the cloud. Ssh generate key ubuntu. In large quantities, SSH keys can become a massive security risk and they can violate compliance requirements.can manage PuTTY keys in addition to OpenSSH and Tectia keys. Managing SSH keysIn larger organizations, the number of SSH keys on servers and clients can easily grow to tens of thousands, in some cases to millions of keys. Then test if login works.
Jun 15, 2015 Hi guys, I've been wracking my brain for weeks on RSA encryption and it turns out the key I had isn't the key at all, its an exponent and I need to use the exponent and modulus I have to generate a key, however it doesn't seem (from what I've found) that Apple has a way of doing that in iOS.
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| 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 |
| #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; |
| } |