[Samsung Galaxy S20 / S20+ / S20 Ultra Questions & ] adfree:
I searched in dd dump of my SM-R875F... for

Samsung corporation

Found first hit... Cert...

Hmmm...

sha512ECDSA

This could answer why Length problem...

I will try to look into SM-G960F or other stuff I have... or floating around...

Best Regards

Edit 1.

Maybe this is DAK folder related...

GAK_RSA.private
GAK_RSA.private.val

With my old blind eyes I can not see RSA 2048 anymore... only higher like RSA 4096...

Edit 2.

Found this...

// Samsung root CA public key.
static const unsigned char ss_ca_pubkey[] = {
0x30, 0x82, 0x01, 0x22, 0x30, 0x0D, 0x06, 0x09, 0x2A, 0x86, 0x48, 0x86, 0xF7, 0x0D, 0x01, 0x01, 0x01, 0x05, 0x00,
0x03, 0x82, 0x01, 0x0F, 0x00, 0x30, 0x82, 0x01, 0x0A, 0x02, 0x82, 0x01, 0x01, 0x00, 0xE0, 0xC2, 0x81, 0x87, 0x55,
0xAF, 0xD2, 0xD1, 0xE0, 0x8D, 0xA3, 0x72, 0x80, 0x23, 0xB9, 0xF6, 0x31, 0x80, 0xDF, 0x09, 0x31, 0x06, 0xDB, 0x52,
0xB0, 0x98, 0x5A, 0x98, 0x6B, 0x1E, 0x5C, 0xF3, 0x50, 0x6D, 0x66, 0xBF, 0x82, 0xA3, 0xAB, 0x26, 0x42, 0x7B, 0x5A,
0x0D, 0xBA, 0x06, 0x3F, 0xE4, 0xE4, 0x0E, 0x86, 0x55, 0xA7, 0x7A, 0x59, 0xA4, 0xC3, 0xD5, 0x6D, 0xC2, 0x9B, 0xC3,
0x7E, 0xC0, 0x38, 0x33, 0x43, 0xC3, 0xBC, 0x85, 0x08, 0xAD, 0x65, 0xEA, 0xEF, 0x5F, 0x68, 0x99, 0x4C, 0xC4, 0xE7,
0x5D, 0x55, 0x95, 0xE4, 0x83, 0x0E, 0x28, 0x12, 0x16, 0x9F, 0xD4, 0xC4, 0xC6, 0x6C, 0x0C, 0xEF, 0x1C, 0x09, 0x80,
0xC1, 0xB5, 0xF9, 0x35, 0x42, 0xE7, 0xC7, 0xEE, 0xCF, 0x86, 0x3A, 0x05, 0xDD, 0x94, 0x1B, 0xAC, 0xC2, 0x7C, 0xDB,
0x20, 0x21, 0x6E, 0x6C, 0x6A, 0xA4, 0x3B, 0x8B, 0xF4, 0x15, 0x25, 0xC9, 0x32, 0xA2, 0x87, 0x00, 0xAA, 0xEE, 0x75,
0xD2, 0xA9, 0xFB, 0x86, 0x0E, 0xDA, 0xD6, 0xC5, 0x7A, 0xBE, 0x76, 0xA8, 0x3B, 0xBD, 0x6E, 0x51, 0x19, 0xA3, 0xD4,
0x20, 0x8B, 0x67, 0x30, 0xDE, 0x23, 0xC2, 0x29, 0x9E, 0x6B, 0xD3, 0xE4, 0xF4, 0x3E, 0x75, 0xFB, 0x85, 0xE0, 0x6E,
0x51, 0x47, 0x14, 0xB2, 0x44, 0x1D, 0xF0, 0xEC, 0xE9, 0xE4, 0xC4, 0xE1, 0x45, 0xFE, 0x50, 0x6C, 0x4E, 0x8A, 0x11,
0xBF, 0x5A, 0xB3, 0x0A, 0x47, 0x0D, 0x20, 0x44, 0x20, 0xCF, 0x8B, 0xE5, 0xCD, 0xF1, 0xE0, 0x1B, 0x77, 0x6E, 0xAD,
0x24, 0xB4, 0x91, 0xD6, 0x9F, 0x4D, 0x0D, 0x4D, 0xE5, 0x32, 0x92, 0x58, 0x4A, 0x74, 0x90, 0x06, 0x6D, 0xD5, 0x5F,
0x51, 0x3A, 0xB1, 0x32, 0xDD, 0x57, 0xFE, 0x5B, 0x02, 0x1E, 0xAF, 0x16, 0x0C, 0x21, 0xC2, 0x5D, 0xD7, 0x5D, 0xB4,
0xA3, 0x24, 0x11, 0xDD, 0x02, 0x03, 0x01, 0x00, 0x01,
};

static const char dev_em_pubkey[] = {
0x30, 0x82, 0x01, 0x22, 0x30, 0x0D, 0x06, 0x09, 0x2A, 0x86, 0x48, 0x86, 0xF7, 0x0D, 0x01, 0x01, 0x01, 0x05, 0x00,
0x03, 0x82, 0x01, 0x0F, 0x00, 0x30, 0x82, 0x01, 0x0A, 0x02, 0x82, 0x01, 0x01, 0x00, 0xC4, 0x9F, 0xCB, 0x96, 0xBA,
0x73, 0x32, 0x2B, 0xB2, 0x25, 0x99, 0x91, 0x0D, 0x33, 0x73, 0xE7, 0xF6, 0x0A, 0xA3, 0x5D, 0x86, 0xFB, 0xA5, 0x28,
0x82, 0x1E, 0x99, 0xFA, 0xD7, 0x8C, 0x32, 0x5E, 0xE9, 0xF8, 0x94, 0x8F, 0xC6, 0xB5, 0xEE, 0xAD, 0x89, 0x6C, 0xBE,
0x00, 0x4B, 0x25, 0x20, 0x30, 0x80, 0xE4, 0xC3, 0x4B, 0xC8, 0x00, 0x1F, 0x37, 0x10, 0x69, 0x13, 0x27, 0x0D, 0x54,
0xD6, 0x2E, 0xBE, 0x54, 0xE9, 0x18, 0x84, 0x85, 0x6D, 0x80, 0x10, 0x10, 0xE8, 0x89, 0xEF, 0x84, 0xD9, 0x00, 0x35,
0xAF, 0x50, 0xD4, 0xE2, 0xD9, 0x10, 0xDB, 0x56, 0xAC, 0x5C, 0xD6, 0x40, 0x7C, 0x69, 0x9E, 0x7A, 0x47, 0x55, 0x7B,
0xA3, 0xFB, 0x59, 0x4B, 0xEC, 0xCC, 0x46, 0x9A, 0x02, 0xEC, 0xA0, 0x3B, 0xA8, 0xCF, 0x46, 0xFB, 0xF0, 0xC5, 0xBA,
0xE4, 0xCC, 0x15, 0xA8, 0xB2, 0x87, 0x92, 0x18, 0xCD, 0x17, 0x53, 0x67, 0x95, 0x61, 0x45, 0x44, 0xF8, 0x64, 0xC2,
0xBB, 0xBE, 0x0B, 0x30, 0x78, 0x44, 0x28, 0x20, 0x2A, 0x2A, 0x73, 0x4E, 0x74, 0xDF, 0x10, 0x6D, 0x95, 0xC0, 0xAC,
0x40, 0x19, 0x44, 0x38, 0x13, 0x44, 0x4C, 0xFC, 0x9A, 0x02, 0x4B, 0x1F, 0xC3, 0x0E, 0x4C, 0x79, 0x96, 0xDA, 0x01,
0x3E, 0x04, 0xDF, 0xD5, 0xE7, 0xE7, 0x6F, 0xB0, 0xE6, 0x5E, 0xDA, 0x49, 0x1F, 0x94, 0x04, 0x15, 0x6D, 0x16, 0xCE,
0x95, 0xB5, 0xAE, 0xE1, 0xDD, 0x39, 0x26, 0xCB, 0xB4, 0xB0, 0xD4, 0x54, 0x93, 0x82, 0xD5, 0x1F, 0xC8, 0xCD, 0xE9,
0x44, 0xB4, 0x9C, 0xFD, 0xBD, 0x21, 0xE5, 0x8A, 0xF0, 0x33, 0x93, 0x63, 0x6A, 0x57, 0x5F, 0xBA, 0x3C, 0x5E, 0x45,
0x6E, 0x18, 0x72, 0x90, 0x90, 0x37, 0xEB, 0x96, 0xDA, 0xC0, 0x0B, 0x76, 0x44, 0x5D, 0x61, 0xF4, 0x85, 0x15, 0xC3,
0xB3, 0x32, 0xC8, 0x4D, 0x02, 0x03, 0x01, 0x00, 0x01
};

Edit 3.

These 2 "public keys" looks like RSA 2048 to me...

And can be found in sboot.bin...

Checked short in:

R870XXU1EVA8
S908BXXU1AVBF