分析recovery升级相关rockchip secure boot specification-en

1、Rockchip Secure Boot and Firmware Encryption Specification文件状态： 草稿 正式发布 正在修改文件标识：Secure Boot当前版本：v1.0作者：完成日期：2013-7-16版 本 历 史1.roductionFor DRM and other applications, Rockchip provides Secure Boot solution to encrypt firmware.Features:..Using SHA1 as HASH function.Using 1024 bits RSA

2、Key.Store and compare RSA Public Key.According to firmware signed or unsigned, enable or disable Secure Boot automatically. When Disable Secure Boot, DRM Key will be deleted and DRM Key Box will be disabled. When Secure Boot enable, system still support Rockchip Loader Rockusb upgrade mode. Loader i

3、s locked after flash Secure Boot firmware.Only the firmware which signed with your offil private key can unlock Loader and flash by RKBatchTool.Only the firmware which signed with your offil private key can use sdcard to upgrade.9.2. Principle2.1 Boot Sequence版本号作者修改日期修改说明v1.02013-7-16初稿Loader use S

4、HA1 to calculate hash value of boot.img/recovery.img.Get signature of boot.img/recovery.img, use public key to decode. Compare these two values are equal or unequal.If equal, enable Secure Boot and DRM key box.If unequal, this is illegal firmware, delete key in DRM key box and disable DRM key box. I

5、f firmware is illegal and Loader is locked, enter Rockusb se.If firmware is illegal and Loader is unlocked, delete DRM key、disable DRM key box and boot system.2.2SecureBootTool Firmware Signed ProcedureSecureBootTool generates public and private key.Using SHA1 to calculate hash value of boot.img/rec

6、overy.img.Using private key to sign hash value and add to boot.img/recovery.img. Packing public key and Loader.Using MD5 to calculate hash value of update.img and signed with private key. This digitalsignature is storedhe end of update.img.2.3 Burning Toolock LoadrocedureThe locked Loader need spel

7、verflash firmware.batch tool to unlock. We dont support other tools toBatch tool will check Loader is locked or unlocked. If Loader is unlocked, it can start flashmode.Batch tool will check update.img is signed or not.Batch tool sends MD5 value of update.img and the digital signature to Loader.Loade

8、r uses its own public key to decrypt the digital signature and compares the two MD5 values. If equal, Loader will be unlocked. If not equal, Loader will inform the firmware isillegal.2.4 Recovery Upgrade ProcedurePubilc key is stored in it when we generate recovery.img.Using public key and getting the digital signature which is decode，then get original MD5 value.Calculate MD5 value of update.img.Compare these two MD5 values.he end of update.img to do RSAIf e