OTA update - Checksum failed. Calculated 0x2b read 0x71

[filipESP]

Hi,
My OTA image is encrypted by AES 128 and it'is the same bin file what it's running.
Partitions table is:

# Name, Type, SubType, Offset, Size, Flags
# Note: if you have increased the bootloader size, make sure to update the offsets to avoid overlap
nvs, data, nvs, 0x9000, 0x4000,
otadata, data, ota, 0xd000, 0x2000,
phy_init, data, phy, 0xf000, 0x1000,
factory, app, factory, 0x10000, 4M,
ota_0, app, ota_0, 0x410000, 4M,
ota_1, app, ota_1, 0x810000, 4M,
storage, data, spiffs, , 0x10000,

When I read client data I must to decrypt bytes before writing memory. Data is decrypted successfull.
( 1740 is a number of last package read by client and has 16 B padding,
first package is reduced by16 B length vector IV. )

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  	if ( !is_first_package ) {
  		mbedtls_base64_decode( (unsigned char*)k_out, 16, &o, (const unsigned char*)k, 24 );

  		  mbedtls_aes_init( &aes );
  		  mbedtls_aes_setkey_dec( &aes, (const unsigned char*) k_out, 16 * 8 );

  		memcpy( iv_out, (const void*)ota_write_data, 16 );
  		memcpy( out, (const void*)ota_write_data + 16, data_read - 16);
  		x = mbedtls_aes_crypt_cbc( &aes, MBEDTLS_AES_DECRYPT, data_read - 16, iv_out, out, (unsigned char*)ota_write);
  		data_to_write = data_read - 16;
  	}
  	else if( packages_no == 1740 ){
  		memcpy( out, (const void*)ota_write_data, BUFFSIZE );
  		x = mbedtls_aes_crypt_cbc( &aes, MBEDTLS_AES_DECRYPT, data_read, iv_out, out, (unsigned char*)ota_write);
  		data_to_write = data_read - 16;
  	} else {
  		memcpy( out, (const void*)ota_write_data, BUFFSIZE );
  		x = mbedtls_aes_crypt_cbc( &aes, MBEDTLS_AES_DECRYPT, data_read, iv_out, out, (unsigned char*)ota_write);
  		data_to_write = data_read;
  	}

So in function:

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esp_ota_write( update_handle, ( const void* )ota_write, data_to_write );

I write only image data without IV and padding.

This is log from console:

I (1296141) HTTP_CLIENT: HTTP_EVENT_ON_HEADER, key=Content-Length, value=1781616
I (1296151) HTTP_CLIENT: HTTP_EVENT_ON_HEADER, key=Content-Type, value=applicati
on/octet-stream
I (1296161) HTTP_CLIENT: HTTP_EVENT_ON_HEADER, key=Date, value=Tue, 31 May 2022
15:01:18 GMT
I (1296171) HTTP_CLIENT: HTTP_EVENT_ON_HEADER, key=Last-Modified, value=Tue, 31
May 2022 09:08:18 GMT
I (1296181) HTTP_CLIENT: HTTP_EVENT_ON_HEADER, key=Strict-Transport-Security, va
lue=max-age=63072000
I (1296191) HTTP_CLIENT: New firmware version: 1.3.0
I (1296201) HTTP_CLIENT: Running firmware version: 1.3.0
I (1351761) HTTP_CLIENT: Connection closed
I (1351761) HTTP_CLIENT: Total Write binary data length: 1781584
I (1351761) esp_image: segment 0: paddr=00410020 vaddr=3f400020 size=ea278h (959
096) map
I (1352071) esp_image: segment 1: paddr=004fa2a0 vaddr=3ffb0000 size=03cb0h ( 15
536)
I (1352081) esp_image: segment 2: paddr=004fdf58 vaddr=40080000 size=020c0h ( 8
384)
I (1352091) esp_image: segment 3: paddr=00500020 vaddr=400d0020 size=ae5fch (714
236) map
I (1352321) esp_image: segment 4: paddr=005ae624 vaddr=400820c0 size=148e4h ( 84
196)
I (1352351) esp_image: segment 5: paddr=005c2f10 vaddr=50000000 size=00010h (
16)
E (1352351) esp_image: Checksum failed. Calculated 0x5e read 0x71
E (1352351) HTTP_CLIENT: Image validation failed, image is corrupted
E (1352361) HTTP_CLIENT: esp_ota_end failed (ESP_ERR_OTA_VALIDATE_FAILED)!
I (1352371) HTTP_CLIENT: HTTP_EVENT_DISCONNECTED

bin file in Windows has 1,69 MB (bytes: 1 781 584)

Calculated checksum is different every time but read is const
Below is 33 bytes from the read checksum byte. Content checked by hex editor.

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71 e7 29 33 df cf 98 93 90 73 19 65 37 60 d5 88
79 d6 8f cb d6 72 b2 77 c0 9c a7 57 ba 48 ff a8 b2

What is the Calculated checksum and how is it computed, since is different evry time ?

[filipESP]

I try to read OTA partition by esptool:

python esptool.py -p COM2 -b 460800 read_flash 0x00410000 0x00400000 out.bin

and I compare with original binary file - size is the same but files are different in 16 B every 1024 B, starting at 1008 Byte.

[filipESP]

Issue resolved.
I didn't declare buffer for IV vector as static and the buffer was clearing every time when I received new package of data.