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Avoid using memory buffer to store the entire pdf document when making a digital signature #20

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Avoid using memory buffer to store the entire pdf document when making a digital signature #20

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4 changes: 2 additions & 2 deletions demo_raster_encoder/demo_raster_encoder.c
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Original file line number Diff line number Diff line change
Expand Up @@ -279,7 +279,7 @@ int write_bitonal_uncompressed_signed_file(t_OS os, const char* filename, const
char* demo = strstr(image_path, "demo_raster_encoder");
strncpy(cert_path, image_path, demo - image_path);
sprintf(cert_path + (demo - image_path), "%s", "certificate.p12");
t_pdfrasencoder* enc = pdfr_signed_encoder_create(PDFRAS_API_LEVEL, &os, cert_path, "");
t_pdfrasencoder* enc = pdfr_signed_encoder_create(PDFRAS_API_LEVEL, &os, filename, cert_path, "");
pdfr_encoder_set_creator(enc, "raster_encoder_demo 1.0");
pdfr_encoder_set_subject(enc, "BW 1-bit Uncompressed sample output");

Expand Down Expand Up @@ -314,7 +314,7 @@ int write_bitonal_uncompressed_signed_and_encrypted_file(t_OS os, const char* fi
char* demo = strstr(image_path, "demo_raster_encoder");
strncpy(cert_path, image_path, demo - image_path);
sprintf(cert_path + (demo - image_path), "%s", "certificate.p12");
t_pdfrasencoder* enc = pdfr_signed_encoder_create(PDFRAS_API_LEVEL, &os, cert_path, "");
t_pdfrasencoder* enc = pdfr_signed_encoder_create(PDFRAS_API_LEVEL, &os, filename, cert_path, "");
pdfr_encoder_set_AES128_encrypter(enc, "open", "master", PDFRAS_PERM_COPY_FROM_DOCUMENT, PD_TRUE);

pdfr_encoder_set_creator(enc, "raster_encoder_demo 1.0");
Expand Down
112 changes: 112 additions & 0 deletions pdfras_digitalsignature/pdfras_digitalsignature.c
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Original file line number Diff line number Diff line change
Expand Up @@ -28,6 +28,16 @@ struct t_digitalsignature {
X509_STORE* cert_store;
};

struct t_sign_file_bio {
FILE* fd;
t_sign_range* ranges;
pdint32 ranges_length;
pdint32 pos;
pduint32 read_bytes;
pdbool eof;
pdbool init;
};

pdbool static load_certificate(t_signer* signer, const char* file, const char* password) {
PKCS12* pkcs12 = NULL;
FILE* pfx_file = NULL;
Expand Down Expand Up @@ -152,6 +162,108 @@ pdint32 pdfr_digsig_signature_length(t_digitalsignature* ds) {
return ret;
}

static int sign_range_bio_create(BIO* b) {
BIO_set_init(b, 1);
return 1;
}

static int sign_range_bio_destroy(BIO* b) {
return 0;
}

static int sign_range_bio_read(BIO* b, char* buf, int len) {
struct t_sign_file_bio* sign_bio_data = BIO_get_data(b);
t_sign_range* ranges = sign_bio_data->ranges;
t_sign_range* current_range;
FILE* fd = sign_bio_data->fd;
int ret = -1;

if (sign_bio_data->eof || sign_bio_data->pos >= sign_bio_data->ranges_length)
return -1;

current_range = &ranges[sign_bio_data->pos];
if (!sign_bio_data->init) {
fseek(fd, current_range->offset, SEEK_SET);
sign_bio_data->init = PD_TRUE;
}
// if length of bytes to read overflow the current range then try
// move to next range or reduce it to the current range boundary
while (sign_bio_data->read_bytes + len > current_range->len) {
int len_ = current_range->len - sign_bio_data->read_bytes;
if (len_ <= 0) {
if (sign_bio_data->pos + 1 >= sign_bio_data->ranges_length) {
sign_bio_data->eof = PD_TRUE;
break;
}
// move to next range
sign_bio_data->pos++;
current_range++;
sign_bio_data->read_bytes = 0;
fseek(fd, current_range->offset, SEEK_SET);
}
else {
len = len_;
}
}
if (!sign_bio_data->eof) {
ret = fread(buf, 1, len, fd);
if (ret > 0) {
sign_bio_data->read_bytes += ret;
}
}

return ret;
}

// sign data from an input file
pdint32 pdfr_digsig_sign_range(t_digitalsignature* ds, FILE* fd, t_sign_range* ranges, pdint32 ranges_length, pduint8* output, const pduint32 output_length) {
assert(ds);
assert(ds->signer);
pdint32 ret = -1;
struct t_sign_file_bio signer_bio_data = {.fd = fd,
.ranges = ranges,
.ranges_length = ranges_length,
.pos = 0,
.read_bytes = 0,
.init = PD_FALSE,
.eof = PD_FALSE
};
BIO_METHOD* meth = BIO_meth_new(BIO_TYPE_FD, "sign-range-content-bio");

BIO_meth_set_read(meth, sign_range_bio_read);
BIO_meth_set_create(meth, sign_range_bio_create);
BIO_meth_set_destroy(meth, sign_range_bio_destroy);

BIO* inputbio = BIO_new(meth);
if (inputbio == NULL)
return -1;

BIO_set_data(inputbio, &signer_bio_data);
PKCS7* pkcs7;
pduint32 flags = PKCS7_DETACHED | PKCS7_BINARY;
pkcs7 = PKCS7_sign(ds->signer->digsig_cert, ds->signer->digsig_pkey, NULL, inputbio, flags);

BIO_free(inputbio);

if (pkcs7) {
BIO* outputbio = BIO_new(BIO_s_mem());
i2d_PKCS7_bio(outputbio, pkcs7);

BUF_MEM* mem = NULL;
BIO_get_mem_ptr(outputbio, &mem);

if (mem && mem->data && output_length >= mem->length) {
ret = (pdint32)mem->length;
memcpy(output, mem->data, mem->length);
}

BIO_free(outputbio);
PKCS7_free(pkcs7);
}

return ret;
}

// sign data
pdint32 pdfr_digsig_sign_data(t_digitalsignature* ds, const pduint8* input, const pdint32 input_length, pduint8* output, const pduint32 output_length) {
assert(ds);
Expand Down
1 change: 1 addition & 0 deletions pdfras_digitalsignature/pdfras_digitalsignature.def
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Original file line number Diff line number Diff line change
Expand Up @@ -7,3 +7,4 @@ EXPORTS
pdfr_digsig_sign_data @4
pdfr_digitalsignature_create_signer @5
pdfr_digitalsignature_validate @6
pdfr_digsig_sign_range @7
10 changes: 9 additions & 1 deletion pdfras_digitalsignature/pdfras_digitalsignature.h
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Expand Up @@ -5,6 +5,7 @@
extern "C" {
#endif

#include <stdio.h>
#include "PdfPlatform.h"

#define DS_DOC_NOT_CHANGED 0x1 // Document has not been changed
Expand All @@ -15,6 +16,10 @@ extern "C" {

typedef struct t_signer t_signer;
typedef struct t_digitalsignature t_digitalsignature;
typedef struct {
pduint32 offset;
pduint32 len;
} t_sign_range;

// Initiliaze digital signature module
// return: t_digitalsignature object
Expand Down Expand Up @@ -48,7 +53,10 @@ typedef pdint32 (PDFRASAPICALL pfn_pdfr_digitalsignature_validate) (t_digitalsig
// output_length: size of buffer for signed data.
// If it smaller than signed data computed in function than function will return -1.
pdint32 PDFRASAPICALL pdfr_digsig_sign_data(t_digitalsignature* ds, const pduint8* input, const pdint32 input_length, pduint8* output, const pduint32 output_length);
typedef pdint32(PDFRASAPICALL *pfn_pdfr_digisig_sign_data) (t_digitalsignature* ds, const pduint8* input, const pdint32 input_length, const pduint8* output, const pduint32 output_length);
typedef pdint32(PDFRASAPICALL *pfn_pdfr_digisig_sign_data) (t_digitalsignature* ds, const pduint8* input, const pdint32 input_length, pduint8* output, const pduint32 output_length);

pdint32 PDFRASAPICALL pdfr_digsig_sign_range(t_digitalsignature* ds, FILE* fd, t_sign_range* ranges, pdint32 ranges_length, pduint8* output, const pduint32 output_length);
typedef pdint32(PDFRASAPICALL* pfn_pdfr_digsig_sign_range) (t_digitalsignature* ds, FILE* fd, t_sign_range* ranges, pdint32 ranges_length, pduint8* output, const pduint32 output_length);

#ifdef __cplusplus
}
Expand Down
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