OpenSC is an open-source project that provides a set of libraries and tools for working with smart cards. It supports a wide range of smart cards and security tokens, enabling users to perform cryptographic operations, manage digital certificates, and interact with various card types using a unified interface.

Pros

• Supports a wide range of smart cards and security tokens
• Cross-platform compatibility (Windows, macOS, Linux)
• Actively maintained with regular updates and security patches
• Extensive documentation and community support

Cons

• Steep learning curve for beginners
• Some advanced features may require in-depth knowledge of smart card technology
• Occasional compatibility issues with certain card types or readers

Code Examples

1. Listing available smart card readers:

#include <stdio.h>
#include <opensc/opensc.h>

int main() {
    sc_context_t *ctx;
    sc_context_param_t ctx_param;
    
    memset(&ctx_param, 0, sizeof(ctx_param));
    sc_context_create(&ctx, &ctx_param);
    
    unsigned int i, reader_count;
    sc_reader_t *readers[SC_MAX_READERS];
    
    reader_count = sc_ctx_get_reader_count(ctx);
    for (i = 0; i < reader_count; i++) {
        printf("Reader %d: %s\n", i, sc_ctx_get_reader(ctx, i)->name);
    }
    
    sc_release_context(ctx);
    return 0;
}

2. Reading a file from a smart card:

#include <stdio.h>
#include <opensc/opensc.h>

int main() {
    sc_context_t *ctx;
    sc_card_t *card;
    sc_path_t path;
    u8 buffer[256];
    size_t buffer_len = sizeof(buffer);
    
    sc_context_create(&ctx, NULL);
    sc_connect_card(ctx, 0, &card);
    
    sc_format_path("3F00", &path);
    sc_select_file(card, &path, NULL);
    
    sc_read_binary(card, 0, buffer, buffer_len, 0);
    
    // Process the read data
    
    sc_disconnect_card(card);
    sc_release_context(ctx);
    return 0;
}

3. Signing data using a private key on the smart card:

#include <stdio.h>
#include <opensc/opensc.h>

int main() {
    sc_context_t *ctx;
    sc_card_t *card;
    sc_pkcs15_card_t *p15card;
    sc_pkcs15_object_t *key_obj;
    sc_pkcs15_prkey_info_t *key_info;
    u8 data_to_sign[] = "Hello, OpenSC!";
    u8 signature[256];
    size_t sig_len = sizeof(signature);
    
    sc_context_create(&ctx, NULL);
    sc_connect_card(ctx, 0, &card);
    sc_pkcs15_bind(card, &p15card);
    
    sc_pkcs15_find_prkey_by_id(p15card, &key_obj->id, &key_obj);
    key_info = (sc_pkcs15_prkey_info_t *)key_obj->data;
    
    sc_pkcs15_compute_signature(p15card, key_obj, SC_ALGORITHM_RSA_PAD_PKCS1,
                                data_to_sign, sizeof(data_to_sign),
                                signature, sig_len);
    
    // Process the signature
    
    sc_pkcs15_unbind(p15card);
    sc_disconnect_card(card);
    sc_release_context(ctx);
    return 0;
}

Getting Started

To get started with OpenSC:

1. Install OpenSC using your package manager or build from