Crypto libraries
OpenSSL II (cont.)
Milan Brož
xbroz@fi.muni.cz
PV181, FI MUNI, Brno
Today’s exercise
 Continue with OpenSSL on Linux
 OpenSSL I/O abstraction (BIO)
 OpenSSL3 ECC (elliptic curves) keygen
 Trivial TLS client
 (optional) some more advanced PKI example
 Bonus: OpenSSL3 providers
Example 7:
OpenSSL BIO (I/O abstraction)
Source/sink BIOs:
BIO_s_mem() - memory I/O
BIO_s_file() - file I/O
BIO_s_fd() - file descriptor IO
BIO_s_socket() - sockets
BIO_s_accept()
BIO_s_connect()
BIO_s_null() - discard (like /dev/null)
Filters
BIO_f_base64() - Base64 encoding
BIO_f_buffer() - buffering I/O
BIO_f_cipher() - encryption/decryption
BIO_f_md() - message digest
BIO_f_ssl() - SSL support for BIO
Example 7: the same encryption as in Example 4 using BIO interface.
See 7_bio_openssl directory.
Example 8:
TLS connection & certificates
BIO TLS connection
- SSL_CTX_set_verify, SSL_get_peer_certificate,
SSL_get_verify_result
- BIO_new_ssl_connect, BIO_get_ssl, BIO_do_connect,
BIO_do_handshake
X509
- X509_STORE_CTX_get_current_cert, X509_print_ex_fp,
X509_NAME_get_entry, …
Connect to https://www.google.com.
Read and validate certificates.
Sent HTTP GET and receive /robots.txt through a secured connection.
See 8_tls_client_openssl directory.
Example 9: ECC keys,
sign & verify with ED25519
EC key (pair) generation
EVP_PKEY_CTX_new_from_name
EVP_PKEY_keygen_init
EVP_PKEY_CTX_set_params
EVP_PKEY_generate
// Also: EVP_EC_gen(), EVP_PKEY_Q_keygen()
Signature – there can be differences for different curves
ED25519: EVP_DigestSign/EVP_DigestVerify (one-shot)
Export of keys and attributes
EVP_PKEY_get_* functions
PEM_write_bio_PrivateKey
PEM_write_bio_PUBKEY
See 9_ecc_gen_openssl3 directory.
(optional example)
Signing and certificates
PKCS12
- PKCS12_verify_mac, PKCS12_parse
PKCS7
- PKCS7_sign, PKCS7_verify
X509
- X509_STORE_add_lookup
BIO
- BIO_new, BIO_new_mem_buf, BIO_new_file
- BIO_push, BIO_f_cipher, BIO_set_cipher
- BIO_flush, BIO_free_all
- d2i_PKCS12_bio, d2i_PKCS7_bio
See opt_cert_sign_openssl directory.
prepare CA signed cert.
script: opt_cert_sign_openssl/create_CA
Bonus: OpenSSL3 providers
You can define you own library;
It is loaded and used through OpenSSL3 API
https://github.com/provider-corner
●
Toy example: Vigenere cipher (historic 16th
century cipher)
git clone https://github.com/provider-corner/vigenere
git submodule init
git submodule update
cmake .
make
●
Need to copy to ossl-modules dir or use config
$ echo ahoj | openssl enc -provider vigenere -e -vigenere -K 000102030405060708090a0b0c0d0e0f
aiqm