SELF - SPRX

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SELF stands for Signed Executable and Linkable Format. SPRX stands for Signed Playstation Relocatable eXecutable. They are the format used by the executables on the PS3 and PSVita.

A screenshot of f0f's presentation at CCC2010.
Self hdr.png

Introduction[edit]

It consists of a CF header with an extended header followed by the encapsulated ELF file. ELF sections can be compressed using gzip. SELFs are encrypted and signed, unlike fSELFs. ELF sections are encrypted using AES128 and signed using ECDSA160 or RSA2048 + HMAC-SHA1 or HMAC-SHA256. SELF file has a specific header called Extended header where it stores all the parameters for this program.

  • Extended Header

It consists of information regarding the structure and offsets of the SELF. The first part is in plaintext until you reach Encryption Root Header.

  • Encryption Root Header

Encryption Root Header is itself encrypted under AES256CBC. It contains key and ivec to further decrypt the Certification data using AES128(CBC or CTR).

  • Certification data

The Certification Header, Certification Body and Certification Footer are encrypted under this AES128 layer and are decrypted with the key above.

  • Certification Header

Certification Header contains the info required to authenticate the Certification. The Certification Footer signature is ECDSA160 of the SHA1 digest of the SELF file starting at offset 0x0 and ending at offset footer_offset, or RSA2048 ?of the same data?.

  • Data Sections

The data sections can be encrypted and/or compressed. SHA1/HMAC-SHA1/HMAC-SHA256 is used to ensure that they have not been modified.

Cryptography[edit]

Here is a small summary on how the SELF cryptography works.

Basically here are the steps being involved by the loaders:

Loaders all have a static key and iv called respectively erk and riv. Those are keys for the first decryption step which are used to decrypt the very first 0x40 bytes of the SELF's metadata using AES256CBC.

Then the result is used as key and iv to decrypt the rest of the Certification data using AES128CTR (PS3) or AES128CBC (PSVita). Finally the decrypted Certification data contains the key and iv for each data sections which are still decrypted following the Segment Certification Header information. This security model is based on the fact that the Certification Root Header once decrypted by the static AES256CBC key in the loader should never be the same from one binary to the other. The same goes for any other value used as an AES128 key or iv.

Loaders are also involved with inflating the binaries using zlib.

The SELF authenticity is based on other independent steps, HMAC-SHA1 or HMAC-SHA256 of the data sections and ECDSA160 or RSA2048 for the signature of the header and the Certification data.

Short references[edit]

More indepth Online course about encryption in generic (also AES/ECDSA): Lecture Notes on Computer and Network Security by Avinash Kak

fSELF[edit]

fSELF stands for fake signed ELF. It is the format ouput by developer SDK. As it name suggests, it is not signed nor encrypted. If it was, that would imply SDK embeds private keys to sign it and keys to encrypt it.

A fSELF has Attribute set to 0x8000. ?always?

A fSELF has usually less rights than a System SELF. The OS recognizes a fSELF by looking at its program-authority-id.

To document more...

Location[edit]

PS3[edit]

Files with extensions: eboot.bin, .self, .sprx.

See also SELFs inside ELFs.

PSVita[edit]

Files with extensions: eboot.bin, .self, .suprx, .skprx.

File Format[edit]

Notes:

  • Warning: PS3 uses big endian, PSVita uses little endian.
  • Encapsulated ELF header fields are useless (only the EI_CLASS EI_DATA and EI_VERSION fields are checked).

PS3 early Program Type 3 SELFs[edit]

SDK 0.60: No sce version nor elf digest
SDK 0.8X: No sce version, with 0x30 elf digest
SDK 0.9X: With sce version and 0x40 elf digest (scetool produces this type)

Special SELFs[edit]

Warhawk public beta release 012[edit]

Oldest official game SELF (not NPDRM !!!) I have found for now: 2007-06-08.

Extended Header[edit]

Extended Header offsets are relative to Certified File start.

Struct[edit]

 typedef struct { // Size is 0x50 bytes
  uint64_t ext_hdr_version;
  uint64_t program_identification_hdr_offset;
  uint64_t ehdr_offset;
  uint64_t phdr_offset;
  uint64_t shdr_offset;
  uint64_t segment_ext_hdr_offset;
  uint64_t version_hdr_offset;
  uint64_t supplemental_hdr_offset;
  uint64_t supplemental_hdr_size;
  uint64_t padding;
 } __attribute__((packed)) ext_hdr;

Table[edit]

field offset type notes
Extended Header version 0x0 u64 3 for PS3, 4 for PSVita
Program Identification Header offset 0x8 u64 Offset to Program Identification Header.
ELF Header offset 0x10 u64 Offset to ELF Header.
Program Header offset 0x18 u64 Offset to ELF Program Header.
Section Header offset 0x20 u64 Offset to ELF Section Header.
Segment Extended Header offset 0x28 u64 Offset to Segment Extended Header.
Version Header offset 0x30 u64 Offset to Version Header.
Supplemental Header offset 0x38 u64 Offset to Supplemental Header.
Supplemental Header size 0x40 u64 Size of Supplemental Header.
Padding 0x48 u64

Comments[edit]

The real ELF data is located after the Extended Header (see Extended Header size in Certified File Header). It is encrypted, unless Certified File attribute is 0x8000 (fake CF). unfself works by cutting the SCE header from the fSELF and if needed decompressing sections.

Program Identification Header[edit]

Temp name was App Info. Official name is Program Identification Header.

Struct[edit]

 typedef struct {
   uint64_t program_authority_id;
   uint32_t program_vender_id;
   uint32_t program_type;
   uint64_t program_sceversion;
   uint64_t padding;
 } __attribute__((packed)) program_identification_header;

Table[edit]

field offset type notes example
program_authority_id 0x00 u64 See Program Authority Id ex: 21 00 00 10 1C CA 01 30
program_vender_id 0x08 u32 See Program Vender Id ex: 00 00 00 00
program_type 0x0C u32 See Program Type ex: 08 00 00 00
program_sceversion 0x10 u64 ?SDK version or app version? version ex: 01.02 is translated by make_fself.exe to 02 01 00 00 ex: 0x0000036000000000 (3.600.011), 0x0000009450000000 (0.945.040)
padding 0x18 u64 Padding 00 00 00 00 00 00 00 00

Comments[edit]

Aligned to 0x10 bytes.

ELF Header[edit]

Struct[edit]

PS3[edit]

typedef struct {
    uint8_t e_ident[16];              /* ELF identification */
    uint16_t e_type;                  /* object file type */
    uint16_t e_machine;               /* machine type */
    uint32_t e_version;               /* object file version */
    uint64_t e_entry;                 /* entry point address */
    uint64_t e_phoff;                 /* program header offset */
    uint64_t e_shoff;                 /* section header offset */
    uint32_t e_flags;                 /* processor-specific flags */
    uint16_t e_ehsize;                /* ELF header size */
    uint16_t e_phentsize;             /* size of program header entry */
    uint16_t e_phnum;                 /* number of program header entries */
    uint16_t e_shentsize;             /* size of section header entry */
    uint16_t e_shnum;                 /* number of section header entries */
    uint16_t e_shstrndx;              /* section name string table index */
} __attribute__((packed)) ELF;

See also specifications: ELF Header ELF-64 Object File Format

PSVita[edit]

typedef struct {
    uint8_t e_ident[16];              /* ELF identification */
    uint16_t e_type;                  /* object file type */
    uint16_t e_machine;               /* machine type */
    uint32_t e_version;               /* object file version */
    uint32_t e_entry;                 /* entry point address */
    uint32_t e_phoff;                 /* program header offset */
    uint32_t e_shoff;                 /* section header offset */
    uint32_t e_flags;                 /* processor-specific flags */
    uint16_t e_ehsize;                /* ELF header size */
    uint16_t e_phentsize;             /* size of program header entry */
    uint16_t e_phnum;                 /* number of program header entries */
    uint16_t e_shentsize;             /* size of section header entry */
    uint16_t e_shnum;                 /* number of section header entries */
    uint16_t e_shstrndx;              /* section name string table index */
} __attribute__((packed)) ELF;
Name of the variable Offset Size Notes
e_ident[0..3] 0 4 Magic.
e_ident[4] 4 1 Class Type. Must be [ELFCLASS32 = 0x01].
e_ident[5] 5 1 Data Type. Must be [ELFDATA2LSB = 0x01].
e_ident[6] 6 1 File version. Must be 1.
e_ident[7...15] 7 9 unused
e_type 0x10 2 See SCE-specific e_type.
e_machine 0x12 2 Must be [EM_ARM = 0x0028].
e_version 0x14 4 Must be 0x1.
e_entry 0x18 4 Address to jump to in order to start program (warning: not always set).
e_phoff 0x1C 4 Boundary checked, but unused (already given by SELF header). ?and for fSELF?
e_shoff 0x20 4 unused
e_flags 0x24 4 unused
e_ehsize 0x28 2 Must be sizeof(Elf32_Ehdr) = 0x0034.
e_phentsize 0x2A 2 Must be sizeof(Elf32_Phdr) = 0x0020.
e_phnum 0x2C 2 Count of Program Header in this ELF.
e_shentsize 0x2E 2 unused
e_shnum 0x30 2 unused
e_shstrndx 0x32 2 unused

See also specifications: yifanlu specs

SCE specific ELF types (e_type)[edit]

/* SCE-specific definitions for e_type: */
#define ET_SCE_EXEC		0xFE00		/* SCE Executable - PRX2 */
#define ET_SCE_RELEXEC		0xFE04		/* SCE Relocatable Executable - PRX2 */
#define ET_SCE_STUBLIB		0xFE0C		/* SCE SDK Stubs */
#define ET_SCE_DYNEXEC		0xFE10		/* SCE EXEC_ASLR (PS4 Executable with ASLR) */
#define ET_SCE_DYNAMIC		0xFE18		/* ? */
#define ET_SCE_IOPRELEXEC	0xFF80		/* SCE IOP Relocatable Executable */
#define ET_SCE_IOPRELEXEC2	0xFF81		/* SCE IOP Relocatable Executable Version 2 */
#define ET_SCE_EERELEXEC	0xFF90		/* SCE EE Relocatable Executable */
#define ET_SCE_EERELEXEC2	0xFF91		/* SCE EE Relocatable Executable Version 2 */
#define ET_SCE_PSPRELEXEC	0xFFA0		/* SCE PSP Relocatable Executable */
#define ET_SCE_PPURELEXEC	0xFFA4		/* SCE PPU Relocatable Executable */
#define ET_SCE_ARMRELEXEC	0xFFA5		/* ?SCE ARM Relocatable Executable (PSVita FW <=0.931) */
#define ET_SCE_PSPOVERLAY	0xFFA8		/* ? */

OS ABI identification[edit]

#define ELFOSABI_CELL_LV2		102	/* CELL LV2 */

ELF Program Segment Header[edit]

Struct[edit]

PS3[edit]

typedef struct
{
  Elf64_Word	p_type;			/* Segment type */
  Elf64_Word	p_flags;		/* Segment flags */
  Elf64_Off	p_offset;		/* Segment file offset */
  Elf64_Addr	p_vaddr;		/* Segment virtual address */
  Elf64_Addr	p_paddr;		/* Segment physical address */
  Elf64_Xword	p_filesz;		/* Segment size in file */
  Elf64_Xword	p_memsz;		/* Segment size in memory */
  Elf64_Xword	p_align;		/* Segment alignment */
} Elf64_Phdr;

PSVita[edit]

typedef struct
{
  Elf32_Word	p_type;			/* Segment type */
  Elf32_Off	p_offset;		/* Segment file offset */
  Elf32_Addr	p_vaddr;		/* Segment virtual address */
  Elf32_Addr	p_paddr;		/* Segment physical address */
  Elf32_Word	p_filesz;		/* Segment size in file */
  Elf32_Word	p_memsz;		/* Segment size in memory */
  Elf32_Word	p_flags;		/* Segment flags */
  Elf32_Word	p_align;		/* Segment alignment */
} Elf32_Phdr;

See Spec here: ELF Program Segment Header

SCE specific segment types (p_type)[edit]

#define PT_SCE_RELA 0x60000000
#define PT_SCE_DYNLIBDATA 0x61000000
#define PT_SCE_PROCPARAM 0x61000001
#define PT_SCE_UNK_61000010 0x61000010
#define PT_SCE_COMMENT 0x6FFFFF00
#define PT_SCE_LIBVERSION 0x6FFFFF01
#define PT_SCE_UNK_70000001 0x70000001
#define PT_SCE_IOPMOD 0x70000080
#define PT_SCE_EEMOD 0x70000090
#define PT_SCE_PSPRELA 0x700000A0
#define PT_SCE_PSPRELA2 0x700000A1
#define PT_SCE_PPURELA 0x700000A4
#define PT_SCE_SEGSYM 0x700000A8

SCE specific segment flags (p_flags)[edit]

*PF_SPU_X = 0x00100000
*PF_SPU_W = 0x00200000
*PF_SPU_R = 0x00400000
*PF_RSX_X = 0x01000000
*PF_RSX_W = 0x02000000
*PF_RSX_R = 0x04000000

ELF Section Header[edit]

Struct[edit]

  typedef struct {
    uint32_t sh_name;                 /* section name */
    uint32_t sh_type;                 /* section type */
    uint64_t sh_flags;                /* section attributes */
    uint64_t sh_addr;                 /* virtual address in memory */
    uint64_t sh_offset;               /* offset in file */
    uint64_t sh_size;                 /* size of section */
    uint32_t sh_link;                 /* link to other section */
    uint32_t sh_info;                 /* miscellaneous information */
    uint64_t sh_addralign;            /* address alignment boundary */
    uint64_t sh_entsize;              /* size of entries, if section has table */
  } __attribute__((packed)) ELF_SHDR;

SCE specific section types (sh_type)[edit]

#define SHT_SCE_RELA 0x60000000
#define SHT_SCE_NID 0x61000001
#define SHT_SCE_IOPMOD 0x70000080
#define SHT_SCE_EEMOD 0x70000090
#define SHT_SCE_PSPRELA 0x700000A0
#define SHT_SCE_PPURELA 0x700000A4

Segment Extended Header[edit]

Temp name was SELF Section Info. Official name is segment_ext_header.

A table which maps each phdr entry to the actual offset/size within the encrypted CF. Indeed, because sections can be compressed, they might not match the values listed within the ELF phdr/shdr.

There is one of these entries for each ELF phdr (ELF Program Segment Header) entry in the ELF file so that the console knows where to decrypt the data from (because it might also be compressed).

Struct[edit]

typedef struct {
  uint64_t offset;
  uint64_t size;
  uint32_t compression;
  uint32_t unknown;
  uint64_t encryption;
} __attribute__((packed)) segment_ext_header;

Table[edit]

field offset type notes
Offset 0x00 u64 Offset to data
Size 0x08 u64 Size of data
Compression 0x10 u32 1 = uncompressed, 2 = compressed
Unknown 0x14 u32 Always 0, as far as I know.
Encryption 0x18 u64 1 = encrypted, 2 = unencrypted

PS3 OS uses the following structure to handle that data:

typedef struct {
  void *data;
  uint64_t size;
  uint64_t offset;
} segment_ext_header;

Version Header[edit]

It contains some version information, including an offset to the .sceversion section of the encrypted ELF.

Struct[edit]

 typedef struct {
  uint32_t subheader_type; // 1 - sceversion
  uint32_t present;        // 0 = false, 1 = true
  uint32_t size;           // usually 0x10
  uint32_t unknown4;
 } __attribute__((packed)) version_header;

Data Struct[edit]

 typedef struct {
  uint16 unknown_1;
  uint16 unknown_2; // 0x1
  uint32 unknown_3;
  uint32 unknown_4; // ?Number of sections?
  uint32 unknown_5;
  ////
    uint64 offset;    // Data offset
    uint64 size;      // Data size
  //// <- these are supposed to be sections
 } SCE_VERSION_DATA_30;

Comments[edit]

Supplemental Header Table[edit]

Temp name was Control Information. Official name is supplemental_header_table.

Struct[edit]

typedef struct ECDSA224_signature { // size is 0x38
   unsigned char r[0x1C];
   unsigned char s[0x1C];
} ECDSA224_signature;

 typedef struct {
  uint32_t type; // 1=PS3 plaintext_capability; 2=PS3 ELF digest; 3=PS3 NPDRM, 4=PSVita ELF digest; 5=PSVita NPDRM; 6=PSVita boot param; 7=PSVita shared secret
  uint32_t size;
  uint64_t next; // 1 if another Supplemental Header element follows else 0

  union {
    // type 1, 0x30 bytes
    struct { // 0x20 bytes of data
      plaintext_capability_t plaintext_capability;
    } PS3_plaintext_capability_header;

    // type 2, 0x40 bytes
    struct { // 0x30 bytes of data
      uint8_t constant[0x14]; // same for every PSVita/PS3 SELF, hardcoded in make_fself.exe: 627CB1808AB938E32C8C091708726A579E2586E4
      uint8_t elf_digest[0x14]; // SHA-1. Hash F2C552BF716ED24759CBE8A0A9A6DB9965F3811C is blacklisted by appldr
      uint64_t required_system_version; // filled on Sony auth server, contains decimal PS3_SYSTEM_VER value from PARAM.SFO
    } PS3_elf_digest_header_40;

    // type 2, 0x30 bytes
    struct { // 0x20 bytes of data
      uint8_t constant_or_elf_digest[0x14];
      uint8_t padding[0xC];
    } PS3_elf_digest_header_30;

    // type 3, 0x90 bytes
    struct { // 0x80 bytes of data
      uint32_t magic;           // 4E 50 44 00 ("NPD.")
      uint32_t license_version;
      uint32_t drm_type;        // [[License Types|license_type]]
      uint32_t app_type;        // [[App Types|app_type]]
      uint8_t content_id[0x30];
      uint8_t digest[0x10];     // SHA-1 hash of debug self/sprx created with make_fself_npdrm
      uint8_t inv_digest[0x10]; // hash_cid_fname (?hash of contentid + filename ?)
      uint8_t xor_digest[0x10]; // hash_cid (?hash of contentid only?)
      uint8_t padding[0x10];
    } PS3_npdrm_header;

     // type 4, 0x50 bytes
     struct { // 0x40 bytes of data
       uint8_t constant[0x14]; // same for every PSVita/PS3 SELF, hardcoded in make_fself.exe: 627CB1808AB938E32C8C091708726A579E2586E4
       uint8_t elf_digest[0x20]; // SHA-256 of source ELF file.
       uint8_t padding[8];
       uint32_t min_required_fw; // ex: 0x363 for 3.63
     } PSVita_elf_digest_header;
     
     // type 5, 0x110 bytes
     struct { // 0x100 bytes of data
       uint32_t magic;               // 7F 44 52 4D (".DRM")
       uint32_t finalized_flag;      // ex: 80 00 00 01
       uint32_t drm_type;            // [[License Types|license_type]] ex: 2 local, 0xD free with license
       uint32_t padding;
       uint8_t content_id[0x30];
       uint8_t digest[0x10];         // ?sha-1 hash of debug self/sprx created using make_fself_npdrm? content_id hash ?
       uint8_t padding_78[0x78];
       ECDSA224_signature sig[0x38]; // signature of PSVita_npdrm_header ? signature of an external NPDRM file ?
     } PSVita_npdrm_header;
     
     // type 6, 0x110 bytes
     struct { // 0x100 bytes of data
       uint8_t boot_param[0x100];
     } PSVita_boot_param_header;
     
     // type 7, 0x50 bytes
     struct { // 0x40 bytes of data
       uint8_t shared_secret_0[0x10]; // ex: 0x7E7FD126A7B9614940607EE1BF9DDF5E or full of zeroes
       uint8_t shared_secret_1[0x10]; // ex: full of zeroes
       uint8_t shared_secret_2[0x10]; // ex: full of zeroes
       uint8_t shared_secret_3[0x10]; // ex: full of zeroes
     } PSVita_shared_secret_header;
  };
 } __attribute__((packed)) supplemental_header;

Table[edit]

Comments[edit]

  • There are 3 digests in ps3_npdrm_header:
    • digest is the sha1 checksum of the entire SELF file.
    • inv_digest is the inverse of digest.
    • xor_digest is digest XORed with 0xAAAAAA..AAAAAB.
  • The PSJailbreak payload ignores the actual checksums, but checks that the 3rd checksum is the 2nd checksum XORed with 0xAAAAAA..AAAAAB.
  • See Capability_Flags.
  • PS3 loader uses supplemental_header_table to handle some data:
typedef struct {
  plaintext_capability_t plaintext_capability;      /* Plaintext Capability */
  uint8[0x14] elf_digest;         /* sha1 hash of the ELF file */
  uint32_t    unknown_0;          /* seems to be padding */
  uint64_t    required_system_vesion;     /* PS3_SYSTEM_VER, decimal format */
} supplemental_header_table;

Extraction[edit]

  • Load the Encryption Root Header and decrypt the key and IV entries using AES256CBC with key and IV from OS.
  • Load the Certification Header and decrypt it using AES128CTR/CBC with the key and IV entries from the Encryption Root Header.
  • Load the Segment Certification Headers and decrypt them using AES128CTR/CBC with the key and ivec entries from the Encryption Root Header.
  • Load the Segment Certifications and decrypt them using AES128CTR/CBC with the key and ivec entries from the Encryption Root Header.
  • For each Segment Certification:
    • In the SELF file, fseek to data_offset and read in data_size bytes.
    • Decrypt the data using the algorithm, key and ivec from the Segment Certification specified by keyIndex and ivecIndex in the Segment Certification Header.
    • Uncompress the data using the algorithm specified in the Segment Certification Header.
    • Write the output data to the ELF file as the program section specified by program_idx in the Segment Certification Header.