zephyr: Add Kconfig option to select PureEdDS

endchoice # BOOT_IMG_HASH_ALG

config BOOT_SIGNATURE_TYPE_PURE_ALLOW

	bool

	help

	  Hidden option set by configurations that allow Pure variant,

	  for example ed25519. The pure variant means that image

	  signature is calculated over entire image instead of hash

	  of an image.

choice BOOT_SIGNATURE_TYPE

	prompt "Signature type"

	default BOOT_SIGNATURE_TYPE_RSA

config BOOT_SIGNATURE_TYPE_ED25519

	bool "Edwards curve digital signatures using ed25519"

	select BOOT_ENCRYPTION_SUPPORT

	select BOOT_IMG_HASH_ALG_SHA256_ALLOW

	select BOOT_ENCRYPTION_SUPPORT if !BOOT_SIGNATURE_TYPE_PURE

	select BOOT_IMG_HASH_ALG_SHA256_ALLOW if !BOOT_SIGNATURE_TYPE_PURE

	# The SHA is used only for key hashing, not for images.

	select BOOT_SIGNATURE_TYPE_PURE_ALLOW

	help

	  This is ed25519 signature calculated over SHA512 of SHA256 of application

	  image.

	  To check signature over entire image directly, rather than hash,

	  select BOOT_SIGNATURE_TYPE_PURE.

if BOOT_SIGNATURE_TYPE_ED25519

config BOOT_SIGNATURE_TYPE_PURE

	bool "Use Pure signature of image"

	depends on BOOT_SIGNATURE_TYPE_PURE_ALLOW

	help

	  The Pure signature is calculated directly over image rather than

	  hash of an image, as the BOOT_SIGNATURE_TYPE_ED25519 does by

	  default.

	  Image to be verified needs to be accessible through memory address

	  space that cryptography functions can access via pointers.

choice BOOT_ED25519_IMPLEMENTATION

	prompt "Ecdsa implementation"

	default BOOT_ED25519_TINYCRYPT

#define MCUBOOT_HASH_STORAGE_DIRECTLY

#endif

#ifdef CONFIG_BOOT_SIGNATURE_TYPE_PURE

#define MCUBOOT_SIGN_PURE

#endif

#ifdef CONFIG_BOOT_BOOTSTRAP

#define MCUBOOT_BOOTSTRAP 1

#endif